Costs & Usage — Full Analysis

Status: Active Owner: @bilal @danny Last Updated: 2026-02-24

TL;DR

Scale	Properties	Infra + Variable	Stripe Fees	Grand Total	Per-Property
Now (dev)	0-5	~$32	—	~$32	N/A
Early users	50	~$83	~$19	~$102	~$2.04
Growth	500	~$418	~$190	~$608	~$1.22
Scale	1,000	~$792	~$380	~$1,172	~$1.17
Target	3,000	~$2,275	~$1,140	~$3,415	~$1.14

Notes: ZTNA (Cloudflare Access) removed when app goes public — saves $420/mo at 3K. Voice is Premium/Partner tier only. Twilio is the dominant cost (65% at scale).

Optimised target (SMS→WhatsApp shift + direct Meta API): ~ $1, 666/ m o in f r a \to * *$ 0.56/property**. At target scale, minimum viable charge is ~$1.50-2/property/mo to break even with margin.

Pricing Validation Log

All prices verified against live pricing pages on 2026-02-23. Prices change frequently — revalidate quarterly.

Service	Doc Price	Verified Price	Source	Status
Cloudflare Workers Paid	$5/mo	$5/mo + 10M req + 30M CPU ms	developers.cloudflare.com/workers/platform/pricing	Correct
Supabase Pro	$25/mo	$25/mo (org-based billing)	supabase.com/pricing	Correct
Supabase Storage overage	$0.021/GB	$0.021/GB	supabase.com/docs/guides/platform/billing-on-supabase	Correct
Supabase Egress	$0.09/GB	$0.09/GB after 250 GB	supabase.com/docs/guides/platform/billing-on-supabase	Correct
Supabase DB overage	$0.125/GB	$0.125/GB after 8 GB disk	supabase.com/docs/guides/platform/billing-on-supabase	Correct
Supabase Auth MAU	$3.25/1K	$0.00325/ M A U ($ 3.25/1K)	supabase.com/docs/guides/platform/billing-on-supabase	Correct
Twilio SMS UK outbound	$0.046	$0.0524	twilio.com/en-us/sms/pricing/gb	UPDATED (+14%)
Twilio UK phone number	~$1/mo	$1.15/mo	twilio.com/en-us/sms/pricing/gb	UPDATED
Claude Sonnet 4.6	$3/$ 15 per MTok	$3/$ 15 per MTok (≤200K ctx)	claude.com/pricing	Correct
Claude Haiku 4.5	—	$1/$ 5 per MTok	claude.com/pricing	New model
OpenAI embeddings	$0.02/MTok	$0.02/MTok (text-embedding-3-small)	openai.com/api/pricing	Correct
Stripe UK standard	1.5% + 20p	1.5% + 20p	stripe.com/gb/pricing	Correct
Stripe Billing	+0.5%	0.7% or from £450/mo annual	stripe.com/gb/pricing	UPDATED — pay-as-you-go is 0.7% not 0.5%
Resend Pro	—	$20/mo (50K emails)	resend.com/pricing	New (replacing SendGrid)
Retell AI	~$0.10/min	$0.07+/min (infra+voice+LLM+telephony)	retellai.com/pricing	UPDATED — component pricing changed

1. Complete Service Inventory

Every service Envo uses or will use, with nothing left out.

#	Service	Component Used	Pricing Model	Current Tier
1	Cloudflare Workers	Dashboard hosting (Next.js via @opennextjs/cloudflare)	$5/mo base + per-request overage	Paid
2	Cloudflare Pages	brain.ehq.tech (Quartz) + ehq.tech marketing site (Astro)	Included in Workers Paid	Paid
3	Cloudflare Hyperdrive	Connection pooling to Supabase Postgres	Included in Workers Paid	Paid
4	Cloudflare DNS	ehq.tech zone, proxied records	Included	Free
5	Cloudflare Access (ZTNA)	Email OTP auth gate for app + brain — will be removed when app goes public	Free ≤50 users	Free (temporary)
6	Supabase — Database	PostgreSQL 16 + pgvector (1536-dim embeddings)	$25/mo Pro, 8 GB disk included	Free*
7	Supabase — Auth	JWT auth, SSR, user sync triggers	100K MAUs included on Pro	Free*
8	Supabase — Storage	3 buckets: issue-attachments (10 MB limit), property-documents (20 MB limit), chat-uploads (5 MB limit)	100 GB included on Pro	Free*
9	~~Supabase — Realtime~~	Not currently used — GraphQL subscriptions via Yoga, not Supabase Realtime	5M messages included (unused)	Free* (included)
10	Supabase — Vault	Encrypted credential storage (pgsodium) for BYOAK	Included on Pro	Free*
11	Anthropic Claude	Primary LLM — Sonnet 4.6 for generation + tool use	$3/ M in p u t,$ 15/M output tokens	Pay-as-you-go
12	OpenAI	Embeddings (text-embedding-3-small) + fallback LLM	$0.02/M tokens (embeddings)	Pay-as-you-go
13	Twilio — SMS	UK outbound notifications to landlords, tenants, vendors	$0.0524/ m s g o u t b o u n d,$ 0.0075/msg inbound	Pay-as-you-go
14	Twilio — WhatsApp	Tenant conversations (primary V1 channel)	$0.005/msg + Meta template fees	Pay-as-you-go
15	Twilio — Phone Numbers	UK numbers for SMS/WhatsApp	$1.15/mo per number	Pay-as-you-go
16	Resend	Email notifications (landlord summaries, vendor assignments)	Free (3K/mo, 100/day) → Pro $20/mo (50K)	Free
17	VAPI / Retell	Voice AI agent for tenant calls	~$0.09-0.17/min all-in	Pay-as-you-go
18	PostHog Cloud EU	Website analytics (cookieless mode, Frankfurt)	Free (1M events/mo) → Growth $0/mo base	Free
19	ehq.tech domain	Domain registration	~$10/yr	Annual
19	Terraform Cloud	IaC state for Cloudflare infra (~15 resources)	Legacy free until Mar 2026	Free (legacy)
20	GitHub	Repo + GitHub Actions CI/CD	Free tier	Free
21	ProtonMail	Team email hosting	Existing Duo plan	Existing
22	Stripe (planned)	Subscription billing, payments	1.5% + 20p per transaction	Not yet

* Supabase is currently on the Free tier for development. Will upgrade to Pro ($25/mo) before any real users. All costings below assume Pro.

2. Fixed Infrastructure (Monthly)

Services that cost the same regardless of property count.

Service	What It Does	Current Cost	Notes
Cloudflare Workers Paid	Dashboard + Pages + Hyperdrive + DNS	$5/mo	10M requests + 30M CPU ms included. Static assets free and unlimited.
Supabase Pro	DB + Auth + Storage + Vault	$25/mo	See Supabase deep-dive below (Realtime not used). Currently on Free for dev.
ehq.tech domain	DNS	*~ $10/ yr * ($ 0.83/mo)	.tech domain renewal
Resend	Email sending	*$0/ m o * (d e v) \to * $ 20/mo* (growth)	Free tier: 3K emails/mo, 100/day limit. Pro at $20/mo for 50K emails/mo.
Terraform Cloud	IaC state	$0	Legacy free tier until Mar 2026
Cloudflare Access	ZTNA auth gate	$0	Free for ≤50 users
GitHub	Repo + CI/CD	$0	Free tier
ProtonMail	Email hosting	$0	Existing Duo plan

**Current fixed total (dev): ~ $31/ m o * * (w i t h S u p aba se P ro :$ 31. Currently ~$6 on Free.)

**Fixed total (growth): ~ $51/ m o * * (w i t h R ese n d P ro a t$ 20/mo)

Supabase Pro Deep-Dive

Everything included in the $25/mo Pro plan and what triggers overages:

Component	Included (Pro)	Overage Rate	When You Hit It
Database (Postgres + pgvector)	8 GB disk per project	$0.125/GB	~500-1,000 properties (est. 2-3 KB/property for core data, but vectors add up — 1536-dim × 4 bytes × chunks)
Auth (MAUs)	100,000	$0.00325/MAU	Unlikely — dashboard users only (tenants don’t have auth accounts)
File Storage	100 GB	$0.021/GB	~5,000+ properties at 5 docs × 2 MB avg = 50 GB for 5K props
Bandwidth / Egress	250 GB	$0.09/GB	High API traffic or large file downloads
Realtime Messages	5,000,000	$2.50/million	Not used — real-time via GraphQL subscriptions (Yoga), not Supabase Realtime
Edge Function Invocations	2,000,000	$2/million	Not currently using edge functions
Compute	Included with project	Add-on pricing	See compute add-on section below

Key insight: Auth MAUs will stay well under 100K because tenants don’t log in via Supabase Auth — they interact via WhatsApp/Voice/Chat. Only dashboard users (landlords, staff) use Supabase Auth. Even at 3,000 properties you’d have maybe 200-500 dashboard users.

Vector storage estimate: At 3,000 properties × 5 docs × 10 chunks × 1536 dimensions × 4 bytes = ~880 MB just for vectors. Add metadata and you’re at ~1-2 GB for vector data alone. Total DB at 3K properties (including conversations, messages, events): est. 15-25 GB.

Supabase Compute Add-Ons

Supabase compute is now priced as explicit add-ons per project (not a tiered upgrade with credits):

Instance	vCPUs	RAM	Approx. Cost/mo	When to use
Micro	2	1 GB	Included (Pro)	Dev / early users
Small	2	2 GB	~$25/mo	~100-300 properties
Medium	2	4 GB	~$50/mo	~300-700 properties
Large	2	8 GB	~$100/mo	~700-1,500 properties
XL	4	16 GB	~$200/mo	~1,500-3,000 properties
2XL	8	32 GB	~$400/mo	3,000+ properties

Note: Exact compute pricing should be verified in the Supabase dashboard as it changes. The above are estimates based on current published rates.

Fixed Cost Scaling Triggers

Trigger	When	Cost Impact
Supabase Free → Pro upgrade	Before any real users	+$25/mo
Supabase compute upgrade (Small)	~100-300 properties	+$25/mo
Supabase compute upgrade (Medium)	~300-700 properties	+$50/mo (replacing Small)
Supabase DB > 8 GB	~500-1,000 properties	+$0.125/GB overage
Supabase storage > 100 GB	Heavy document uploads	+$0.021/GB overage
Supabase bandwidth > 250 GB	High API traffic	+$0.09/GB overage
~~Cloudflare Access > 50 users~~	~~50+ dashboard users~~	~~$7/user/mo for ALL users~~ — ZTNA will be disabled when app goes public
Terraform Cloud free tier ends	Mar 2026	~ $0.10/ reso u rce / m o (15 reso u rces \approx$ 1.50/mo)
Resend Free → Pro upgrade	>3K emails/mo OR >100/day	+$20/mo
Resend Pro → Scale upgrade	>50K emails/mo	+ $70/ m o (f ro m$ 20 → $90)
Workers > 10M requests/mo	Very high scale	+$0.30 per million requests
Supabase Team plan (for SAML)	White-label Partner tier	Jump from $25 \to$ 599/mo

3. Variable Costs — Per-Conversation AI

The biggest variable cost driver. Each tenant conversation involves LLM calls for intent classification, tool-use orchestration, and RAG generation.

Cost Per Conversation Breakdown

Based on ADR-017 and RAG Pipeline docs, a typical issue-reporting conversation has ~4-6 turns.

Component	Cost Per Turn	Cost Per Conversation (5 turns)
Claude Sonnet 4.6 (generation + tool use)	~$0.003-0.01	~$0.015-0.05
Claude Haiku 4.5 (reranking, future)	~$0.001-0.003	~$0.005-0.015
OpenAI embeddings (query)	~$0.0001	~$0.0005
Total AI per conversation		~$0.02-0.06

Cost Per Q&A Query (no issue created)

Simpler — typically 1-2 turns.

Component	Cost
Claude generation	~$0.01-0.03
OpenAI embedding query	~$0.0001
Total per Q&A	~$0.01-0.03

Document Ingestion (One-Time Per Document)

Component	Cost Per Document
Text extraction	$0 (local)
Chunking + embedding (avg 10 chunks)	~$0.0002
Total per document	~$0.001 (negligible)

4. Variable Costs — Notifications & Messaging

Clarification: What Uses What

Channel	Used For	Provider
WhatsApp	Tenant conversations (primary inbound channel)	Twilio as BSP (see migration path below)
SMS	Outbound notifications to landlords, tenants, vendors	Twilio
Email	Non-urgent notifications, summaries, vendor assignments	Resend

Important: Twilio is the BSP (Business Solution Provider) for WhatsApp, not the messaging platform itself. Meta’s WhatsApp Business API is the underlying service — Twilio just provides the API wrapper and phone number hosting.

SMS Notification Cost Per Issue

Event	Channel	Recipients	Cost Per Message	Subtotal
Issue created	SMS to landlord	1	$0.0524	$0.0524
Issue created	Email to landlord	1	~$0.0004	~$0.0004
Issue created	SMS confirmation to tenant	1	$0.0524	$0.0524
Vendor assigned	SMS + Email to vendor	1	$0.0524 +$ 0.0004	$0.053
Vendor accepts	SMS to landlord + tenant	2	$0.0524 × 2	$0.1048
Issue completed	Email to landlord + tenant	2	~$0.0004 × 2	~$0.001
Total per issue lifecycle				~$0.26

WhatsApp Costs (Tenant Conversations)

Item	Via Twilio BSP	Direct Meta Business API
Twilio per-message markup	$0.005/msg	N/A
Meta utility template (UK)	~$0.02/template	~$0.02/template
Meta service conversations	First 1,000/mo free	First 1,000/mo free
Avg conversation (8 msgs)	~$0.04-0.20	~$0.00-0.16

WhatsApp Migration Path: Twilio → Direct Meta Business API

Twilio adds a $0.005/msg markup on top of Meta’s own fees. At scale this adds up:

Scale	WhatsApp msgs/mo	Twilio markup saved	Annual saving
500 props	6,000	$30/mo	$360/yr
1,000 props	12,000	$60/mo	$720/yr
3,000 props	36,000	$180/mo	$2,160/yr

Migration options:

Direct Meta WhatsApp Business API — Use Meta’s Cloud API directly. Eliminates Twilio markup entirely. Requires webhook hosting (already have Cloudflare Workers) and number porting. Meta conversation pricing still applies.
BYOAK for WhatsApp (ADR-014) — Partner-tier orgs bring their own Meta Business account or Twilio credentials. Shifts entire WhatsApp cost to customer.
Alternative BSPs — 360dialog, MessageBird/Bird, Infobip offer lower per-message markups than Twilio ( $0.001 - 0.003 v s$ 0.005).

Recommendation: Start with Twilio (fastest to ship), plan migration to direct Meta Cloud API by ~500 properties. The $0.005/msg markup is acceptable at low scale but worth eliminating at 1K+.

SMS: Keep or Replace?

SMS is used only for outbound notifications (not conversations). Options:

Option	Cost/msg	Pros	Cons
Twilio SMS (current)	$0.0524	Already integrated, reliable	Most expensive
Shift to WhatsApp for tenant notifications	~$0.005-0.02	2-10× cheaper than SMS	Requires tenant opt-in, not all tenants on WhatsApp
Email-first for non-urgent	~$0.0004	Cheapest	Slower, may be missed
Push notifications (future mobile app)	~$0	Free	Requires app adoption

Recommendation: Default to WhatsApp for tenant notifications where possible (they’re already on the channel), SMS only as fallback for tenants without WhatsApp, email for non-urgent/digest. This alone could cut notification costs by 50-70%.

Email Provider: Resend (Replacing SendGrid)

We have not yet committed to an email provider. After evaluation:

Provider	Free Tier	Paid Tier	Pros	Cons
Resend (recommended)	3K emails/mo, 100/day	Pro: $20/mo for 50K	Modern DX, React Email, good free tier, better webhook support	Newer, smaller company
SendGrid	60-day free trial only	Essentials: $19.95/mo for 50K	Established, Twilio ecosystem	Free trial expires, worse DX
Postmark	100 emails/mo free	$15/mo for 10K	Best deliverability reputation	Expensive at scale
Amazon SES	3K/mo free (from EC2)	$0.10/1K emails	Cheapest at scale	Setup complexity, no dashboard

Decision: Resend — Free tier covers dev, Pro ($20/mo) is competitive, and React Email integration aligns with our React/Next.js stack. The @sendgrid/mail package currently in package.json should be replaced with Resend’s SDK when email integration is implemented.

At 3,000 properties (est. ~6K emails/mo), Resend’s Free tier might actually suffice if daily limits aren’t hit. Pro at $20/mo gives comfortable headroom.

5. Variable Costs — Voice AI (VAPI / Retell)

Voice is the most expensive per-interaction channel.

Retell All-In Cost (Verified 2026-02-23)

Retell now uses component-based pricing:

Component	Per Minute	Notes
Retell Voice Infra	$0.055	Platform + orchestration
TTS (Cartesia/Minimax/ElevenLabs)	$0.015	All voice providers same price
LLM (Claude 3.5 Haiku)	$0.020	Cheapest Claude option
LLM (Claude 3.7 Sonnet)	$0.060	Higher quality
Telephony (Retell Twilio, UK)	$0.10	UK international rate
Telephony (Custom/SIP)	$0.00	BYO telephony = free
Total (Haiku + Retell Twilio UK)	~$0.19/min
Total (Haiku + Custom telephony)	~$0.09/min
Total (Sonnet + Custom telephony)	~$0.13/min

VAPI All-In Cost (Estimated)

VAPI’s pricing page did not render detailed rates. Previous estimates:

Component	Per Minute
Platform fee	$0.05
STT (Deepgram)	~$0.01
LLM (Claude Sonnet)	~$0.06
TTS (ElevenLabs)	~$0.04
Telephony (Twilio)	~$0.01
Total	~$0.17/min

Note: VAPI pricing should be re-verified directly. These are previous estimates.

Voice Cost Per Conversation

Average maintenance call: 3-5 minutes.

Provider	Config	3-Min Call	5-Min Call
Retell (Haiku + custom telephony)	Budget	$0.27	$0.45
Retell (Sonnet + custom telephony)	Quality	$0.39	$0.65
Retell (Haiku + Retell Twilio UK)	Default	$0.57	$0.95
VAPI (est.)	Default	$0.51	$0.85

Voice is 10-20× more expensive per interaction than chat/WhatsApp. Channel mix matters enormously for cost.

Voice Pricing Model Options

Given voice costs $0.27-0.95 per call, including it in a flat per-unit fee creates margin risk. Options:

Model	How It Works	Pros	Cons
Tier-gated	Voice only on Premium/Partner (£5+/unit)	Protects Basic margins; upsell lever	Limits adoption of best demo feature
Usage-based add-on	Base plan + voice at £0.10-0.15/min billed to org	Perfect cost alignment; transparent	Unpredictable bills; friction
Included with cap	e.g. 5 voice minutes/unit/mo on Premium, overage at cost	Predictable for customer; capped risk	Still subsidising voice
Per-call flat fee	e.g. £0.50/call charged to org	Simple to understand	May discourage usage

Recommendation: Voice as a Premium/Partner tier feature with an included cap (e.g. 5 min/unit/mo). This:

Keeps Basic tier margins healthy (no voice subsidy)
Creates a strong upsell path (“upgrade to get the AI phone line”)
Caps Envo’s exposure on heavy voice users
Aligns with the pricing analysis recommendation (voice in Premium at £5/unit)

For Partner-tier BYOAK orgs, they bring their own VAPI/Retell account — voice cost shifts entirely to them.

Impact on Scaling Model

If voice is tier-gated (not in Basic), the cost milestones change significantly:

Scale	With voice in all tiers	Voice in Premium/Partner only (est. 30% of properties)
500 props	$52/mo	~$16/mo
1,000 props	$104/mo	~$31/mo
3,000 props	$312/mo	~$94/mo

Moving voice to Premium saves ~$218/mo at 3K scale.

6. Stripe Payments Integration

When billing is implemented (ADR-004):

Stripe Fees (Verified 2026-02-23)

Fee Type	Rate
UK standard card processing	1.5% + 20p per transaction
UK premium card processing	1.9% + 20p
EEA cards	2.5% + 20p
International cards	3.25% + 20p
Stripe Billing (subscriptions) — pay-as-you-go	+0.7% per recurring payment
Stripe Billing (annual contract)	From £450/mo
Stripe Connect (if marketplace)	Starting at 0.25% per transaction
Disputes	£20 each
Currency conversion	+2% if required

Example at Scale

Using Stripe Billing pay-as-you-go (0.7% + card processing):

Scale	Properties	Monthly Revenue (£15/property assumed)	Stripe Fees (est. 2.2% effective)
50	50	£750	~~£26 (~~$33)
500	500	£7,500	~~£195 (~~$247)
1,000	1,000	£15,000	~~£375 (~~$475)
3,000	3,000	£45,000	~~£1,080 (~~$1,368)

Note: Effective rate improves at scale because the 20p fixed fee becomes proportionally smaller. Using 2.2% (1.5% card + 0.7% Billing) as base estimate. If most payments are via Direct Debit (Bacs at 1% capped at £4), effective rate could be lower.

Correction from previous version: Stripe Billing is 0.7% pay-as-you-go, not 0.5%. Annual contract option (from £450/mo) may be more cost-effective at scale.

Stripe Connect Consideration

If offering white-label billing where landlords charge their tenants through Envo, Stripe Connect adds 0.25%+ per transaction. This is relevant for the Partner tier (ADR-014).

7. White-Labelling Cost Implications (ADR-014)

Cost Shifts by Tier

Tier	Cost Impact
Basic	All costs on Envo’s shared accounts
Premium (BYOAK)	Org pays own Resend + LLM → Envo’s variable costs drop
Partner (full white-label)	Org pays own Twilio + VAPI + LLM → Envo’s costs are nearly fixed only

BYOAK Cost Savings for Envo

When a Premium/Partner org brings their own API keys:

LLM costs shift to org: saves ~$0.02-0.06 per conversation
Email costs shift to org: saves ~$20/mo per org
Twilio costs shift to org: saves ~$0.05-0.26 per notification

White-Label Infrastructure Costs

Feature	Cost to Envo
Custom domains (Partner)	Cloudflare custom hostname — included in Workers plan
Supabase Vault (credential storage)	Included in Supabase Pro
SSO/SAML (Partner)	Depends on provider — Supabase Auth supports SAML on Team plan ($599/mo)

Key Risk: Supabase SAML

SSO/SAML is only available on Supabase Team plan ( $599/ m o) or E n t er p r i se . T hi s i s a s i g ni f i c an t j u m p f ro m P ro ($ 25/mo). Consider whether SSO can be handled at the Cloudflare Access layer instead (which supports SAML on paid plans).

8. Scaling Model — Full Cost at Milestones

Assumptions

Issues per property per month: 1.5 (HMO avg)
Conversations per property per month: 2 (issues + Q&A)
Messages per conversation: 6
Notifications per issue: 5 (SMS + email mix)
Voice calls: 10% of conversations
Avg voice call duration: 4 minutes
Documents per property: 5 (one-time ingestion)
Channel mix: 60% WhatsApp, 30% chat, 10% voice
Dashboard users: 1 per 50 properties (staff + landlords)

Dev / Now (0-5 Properties)

Cost Centre	Monthly
Cloudflare Workers Paid	$5.00
Supabase Pro*	$25.00
Resend (Free tier — <100 emails/day)	$0.00
Domain (amortised)	$0.83
Terraform Cloud	$0.00
Twilio phone number (1 UK number)	~$1.15
LLM / AI (minimal testing)	~$0.50
Twilio SMS / WhatsApp	~$1.00
Total	~$34

* Currently on Supabase Free — actual dev cost is ~$8/mo. Will upgrade to Pro before real users.

50 Properties

Cost Centre	Monthly
Cloudflare (Workers + Pages + Hyperdrive + DNS)	$5
Supabase Pro (DB ~1 GB, Auth ~50 MAUs, Storage ~5 GB)	$25
Resend Free (1,500 emails/mo — within 3K/mo limit)	$0
Twilio phone numbers (2 UK)	$2.30
LLM — Claude Sonnet (100 convos × $0.04)	$4
LLM — OpenAI embeddings (250 docs × $0.001)	$0.25
Twilio SMS (75 issues × 5 notifications × $0.0524)	$19.65
Twilio WhatsApp (60 convos × $0.10)	$6
Voice AI (10 calls × 4 min × $0.13)	$5
Supabase Storage (issue attachments ~2 GB)	$0 (within 100 GB)
~~CF Access~~	$0 (ZTNA removed when public)
Infra + variable total	~$67
+ Stripe fees (£750 revenue × ~2.2%)	~~£17 (~~$21)
Grand total	~$88

Note: At 50 properties, Resend Free tier may suffice (est. 1,500 emails/mo < 3K limit). But the 100/day limit could be tight on busy days — upgrade to Pro ( $20/ m o) i f n ee d e d . Wi t h R ese n d P ro :$ 88.

500 Properties

Cost Centre	Monthly
Cloudflare (Workers + Pages + Hyperdrive)	$5
Supabase Pro (DB ~4 GB, Auth ~200 MAUs, Storage ~25 GB)	$25
Supabase compute upgrade (Small)	$25
Resend Pro (~15K emails/mo)	$20
Twilio phone numbers (3 UK)	$3.45
LLM — Claude Sonnet (1,000 convos × $0.04)	$40
LLM — OpenAI embeddings (queries, negligible)	$1
Twilio SMS (750 issues × $0.26 per lifecycle)	$195
Twilio WhatsApp (600 convos × $0.10)	$60
Voice AI (100 calls × 4 min × $0.13)	$52
Supabase Storage (attachments + docs ~20 GB)	$0 (within 100 GB)
~~CF Access~~	$0 (ZTNA removed when public)
Infra + variable total	~$427
+ Stripe fees (£7,500 revenue × ~2.2%)	~~£165 (~~$209)
Grand total	~$636

1,000 Properties

Cost Centre	Monthly
Cloudflare (Workers + Pages + Hyperdrive)	$5
Supabase Pro (DB ~10 GB, Auth ~400 MAUs, Storage ~50 GB)	$25
Supabase DB overage (2 GB × $0.125)	$0.25
Supabase compute upgrade (Medium)	$50
Resend Pro (~30K emails/mo)	$20
Twilio phone numbers (5 UK)	$5.75
LLM — Claude Sonnet (2,000 convos × $0.04)	$80
LLM — OpenAI embeddings	$2
Twilio SMS (1,500 issues × $0.26)	$390
Twilio WhatsApp (1,200 convos × $0.10)	$120
Voice AI (200 calls × 4 min × $0.13)	$104
Supabase Storage (attachments + docs ~40 GB)	$0 (within 100 GB)
~~CF Access~~	$0 (ZTNA removed when public)
Infra + variable total	~$802
+ Stripe fees (£15K revenue × ~2.2%)	~~£330 (~~$418)
Grand total	~$1,220

3,000 Properties (Target Scale)

Cost Centre	Monthly
Cloudflare (Workers ~5M req/mo + Pages + Hyperdrive)	$5
Supabase Pro (DB ~25 GB, Auth ~800 MAUs, Storage ~120 GB)	$25
Supabase DB overage (17 GB × $0.125)	$2.13
Supabase Storage overage (20 GB × $0.021)	$0.42
Supabase bandwidth overage (est. 50 GB over)	$4.50
Supabase compute upgrade (Large)	$100
Resend Scale (~80K emails/mo, need dedicated IP)	$90
Twilio phone numbers (10 UK)	$11.50
LLM — Claude Sonnet (6,000 convos × $0.04)	$240
LLM — Claude Haiku reranking (ADR-018)	$36
LLM — OpenAI embeddings	$5
Twilio SMS (4,500 issues × $0.26)	$1,170
Twilio WhatsApp (3,600 convos × $0.10)	$360
Voice AI (600 calls × 4 min × $0.13) — Premium/Partner only	$312
~~CF Access~~	$0 (ZTNA removed when public)
Terraform Cloud (~15 resources × $0.10)	$1.50
Infra + variable total	~$2,363
+ Stripe fees (£45K revenue × ~2.2%)	~~£990 (~~$1,253)
Grand total	~$3,616

If voice is tier-gated (Premium/Partner only, ~30% of properties): voice drops to ~ $94/ m o \to t o t a l$ 2,145.

9. Cost Breakdown by Category (at 3,000 Properties)

With ZTNA removed (app is public) and voice as Premium/Partner only:

Category	Monthly	% of Total
Twilio (SMS + WhatsApp)	$1,542	65%
Voice AI (Premium/Partner only)	$312	13%
LLM (Claude + OpenAI)	$281	12%
Supabase (DB + Auth + Storage + Compute)	$132	6%
Resend	$90	4%
Other fixed (CF Workers, domain, TF)	$7	<1%
Total	~$2,363

Twilio is the dominant cost at scale — nearly two-thirds of total costs. This makes the WhatsApp migration path (Twilio → direct Meta API) and SMS → WhatsApp notification shift the two highest-impact optimisations.

Where Each Dollar Goes (per property per month at 3K)

Category	Per Property
Twilio SMS (notifications)	$0.39
Twilio WhatsApp (conversations)	$0.12
Voice AI (if Premium/Partner)	$0.10
LLM (generation + reranking)	$0.09
Supabase	$0.04
Resend	$0.03
Other	<$0.01
Total infra per property	$0.79
+ Stripe pass-through	$0.42

With Optimisations Applied

If you shift SMS notifications to WhatsApp where possible and migrate to direct Meta API:

Optimisation	Saving at 3K
SMS → WhatsApp for tenant notifications (~60% shift)	-$450/mo
Twilio → Direct Meta API ($0.005/msg markup removed)	-$180/mo
Optimised total	*~ $1, 733/ m o * ($ 0.58/property)

10. Supabase Cost Deep-Dive: Storage Migration & Scaling

Supabase Storage is currently used for three buckets: issue-attachments, property-documents, and chat-uploads. At scale, this becomes a meaningful cost centre. Here’s a detailed analysis of whether migration makes sense.

Current Storage Architecture

Bucket	File Size Limit	Est. Growth Rate	At 3K Properties
issue-attachments	10 MB	~5 MB/issue × 1.5 issues/prop/mo	~27 GB/year growth
property-documents	20 MB	~5 docs × 2 MB/doc = 10 MB/prop (one-time)	~30 GB (one-time, then slow growth)
chat-uploads	5 MB	~0.5 MB/conversation avg	~18 GB/year growth
Total at 3K after Year 1			~75 GB
Total at 3K after Year 2			~120 GB (exceeds 100 GB included)

When Storage Becomes a Cost Issue

Time	Est. Total Storage	Supabase Cost	Overage
Year 1 at 3K	~75 GB	$0 (within 100 GB)	None
Year 2 at 3K	~120 GB	$0.42/ m o (20 GB \times$ 0.021)	Minimal
Year 3 at 3K	~165 GB	$1.37/ m o (65 GB \times$ 0.021)	Still cheap
Year 3 at 3K + heavy use	~250 GB	$3.15/ m o (150 GB \times$ 0.021)	Manageable

Key finding: Supabase Storage overage at $0.021/ GB i s v eryc h e a p . E v e na t 250 GB o f s t or a g e, t h eo v er a g e i so n l y$ 3.15/mo. The storage cost is not a significant scaling concern.

Bandwidth/Egress Is the Real Risk

Storage costs are cheap, but downloading files is where costs scale:

Scenario	Monthly Egress	Supabase Cost
Dashboard users viewing attachments (low)	~50 GB	$0 (within 250 GB)
Dashboard users + tenant-facing docs (medium)	~200 GB	$0 (within 250 GB)
Heavy API usage + document serving (high)	~500 GB	$22.50/ m o (250 GB \times$ 0.09)
CDN-less direct serving at scale	~1 TB	$67.50/mo

Migration Options: Should We Move Storage?

Option	Storage Cost	Egress Cost	Pros	Cons
Stay on Supabase Storage (current)	$0.021/GB	$0.09/GB after 250 GB	Simple, integrated, RLS policies, no migration needed	Egress costs at very high scale
Cloudflare R2	$0.015/GB/mo	$0 egress	Zero egress costs, same Cloudflare ecosystem	Separate integration, no RLS, need signed URLs
Cloudflare R2 + Supabase proxy	$0.015/GB/mo	$0 egress	Best of both: zero egress + Supabase auth layer	Complexity of proxy setup
S3 + CloudFront	$0.023/GB/mo	$0.085/GB	Industry standard, mature	AWS complexity, vendor sprawl

Recommendation: Stay on Supabase, Plan R2 Migration at 3K+

Now → 1,000 properties: Stay on Supabase Storage. Costs are negligible ($0-3/mo for storage). Egress stays within 250 GB included.
1,000-3,000 properties: Monitor egress. If dashboard + API traffic pushes egress past 300-400 GB/mo, begin R2 evaluation.
3,000+ properties: Migrate property-documents and issue-attachments to Cloudflare R2. Keep chat-uploads on Supabase (small files, tightly coupled to conversations).
- R2 at 3K properties (120 GB storage): $1.80/ m os t or a g e +$ 0 egress vs Supabase ~ $3.15/ m os t or a g e + u pt o$ 22.50/mo egress = saves $0-24/mo.
- Not worth the migration effort below 3K properties unless egress becomes a problem.
Alternative: Put Cloudflare CDN in front of Supabase Storage URLs (cache at edge, reduce egress). This is the lowest-effort option and may defer R2 migration indefinitely.

Supabase Cost Scaling Summary

Scale	DB (disk)	Storage	Compute	Egress	Auth	Total Supabase
Dev (0-5)	$0 (within 8 GB)	$0 (within 100 GB)	Included (Micro)	$0 (within 250 GB)	$0 (within 100K MAU)	$25 (Pro base)
50	$0	$0	Included	$0	$0	$25
500	$0 (~4 GB)	$0 (~25 GB)	$25 (Small)	$0 (~100 GB)	$0 (~200 MAU)	$50
1,000	$0.25 (10 GB, 2 GB over)	$0 (~50 GB)	$50 (Medium)	$0 (~200 GB)	$0 (~400 MAU)	$75
3,000	$2.13 (25 GB, 17 GB over)	$0.42 (120 GB, 20 GB over)	$100 (Large)	$4.50 (300 GB, 50 GB over)	$0 (~800 MAU)	$132

Supabase compute is the dominant Supabase cost — not storage, not egress, not DB size. At 3K properties, compute is 76% of the total Supabase bill.

Supabase Compute Optimisation Strategies

Strategy	Potential Saving	Effort
Connection pooling via Hyperdrive	Already done — prevents connection exhaustion	Done
Read replicas (Supabase add-on)	Offload reads, keep smaller primary compute	Medium
Query optimisation (indexes, N+1 prevention)	Can delay compute upgrades by 30-50%	Ongoing
Cache hot queries (Redis/KV at edge)	Reduce DB load significantly	Medium-High
Migrate to self-managed Postgres (Neon, Railway, etc.)	More control over compute costs	High (lose Supabase Auth/Storage/RLS)

Recommendation: Optimise queries and use Hyperdrive (already done) before upgrading compute. Add read replicas at 1K+ properties if primary becomes bottleneck. Do not migrate off Supabase — the integrated Auth + Storage + RLS + Vault is worth the compute premium.

11. Key Sensitivities

Variable	Impact
Voice call volume	+10% voice adoption = +$360/mo at 3K scale
Issues per property	Each +0.5 issues/property/mo = + $390 SMS +$ 80 LLM at 3K
WhatsApp vs SMS mix	Shifting notifications from SMS → WhatsApp saves ~50-70%
Twilio → Direct Meta API	Removes $0.005/ m s g ma r k u p \to s a v es$ 180/mo at 3K
BYOAK adoption	Premium/Partner orgs shifting own keys saves $0.04+/conversation
Claude model choice	Haiku vs Sonnet = 3× cheaper LLM costs
Voice pricing model	Tier-gating voice to Premium saves ~$218/mo vs including in all tiers
SMS rate increase	Twilio UK SMS is $0.0524 (u p f ro m$ 0.046) — 14% increase affects all SMS projections
Stripe Billing fee	0.7% pay-as-you-go (up from previously assumed 0.5%) — affects payment projections
Supabase compute	Largest Supabase cost — query optimisation can delay upgrades significantly

12. Recommendations: DB Data for Better Estimates

To replace these back-of-envelope numbers with real data, query the dev DB for:

Conversation Metrics

-- Average messages per conversation
SELECT
  AVG(msg_count) AS avg_messages,
  PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY msg_count) AS median_messages,
  PERCENTILE_CONT(0.95) WITHIN GROUP (ORDER BY msg_count) AS p95_messages
FROM (
  SELECT conversation_id, COUNT(*) AS msg_count
  FROM messages
  GROUP BY conversation_id
) t;
 
-- Conversations per property per month
SELECT
  DATE_TRUNC('month', c.started_at) AS month,
  c.property_id,
  COUNT(*) AS conversations
FROM conversations c
WHERE c.property_id IS NOT NULL
GROUP BY 1, 2;
 
-- Channel distribution
SELECT channel, COUNT(*) AS count,
  ROUND(COUNT(*)::NUMERIC / SUM(COUNT(*)) OVER () * 100, 1) AS pct
FROM conversations
GROUP BY channel;

Issue Metrics

-- Issues per property per month
SELECT
  DATE_TRUNC('month', created_at) AS month,
  property_id,
  COUNT(*) AS issues
FROM issues
WHERE deleted_at IS NULL
GROUP BY 1, 2;
 
-- Notifications per issue (from issue_events)
SELECT
  ie.issue_id,
  COUNT(*) FILTER (WHERE ie.event_type = 'NOTIFICATION_SENT') AS notifications
FROM issue_events ie
GROUP BY ie.issue_id;

Voice Metrics

-- Voice conversation duration
SELECT
  AVG(m.audio_duration_seconds) AS avg_seconds,
  SUM(m.audio_duration_seconds) AS total_seconds,
  COUNT(DISTINCT m.conversation_id) AS voice_conversations
FROM messages m
JOIN conversations c ON m.conversation_id = c.id
WHERE c.channel = 'VOICE'
  AND m.audio_duration_seconds IS NOT NULL;

Storage Metrics

-- Total document storage
SELECT
  COUNT(*) AS total_docs,
  SUM(file_size) / 1024 / 1024 AS total_mb,
  AVG(file_size) / 1024 AS avg_kb
FROM property_documents
WHERE deleted_at IS NULL;
 
-- Chunks per document (for embedding cost)
SELECT
  AVG(chunk_count) AS avg_chunks,
  MAX(chunk_count) AS max_chunks
FROM (
  SELECT document_id, COUNT(*) AS chunk_count
  FROM document_chunks
  GROUP BY document_id
) t;
 
-- Attachment storage
SELECT
  COUNT(*) AS total_attachments,
  SUM(file_size) / 1024 / 1024 AS total_mb
FROM attachments;

Token Usage (If Logged)

If you instrument LLM calls to log token counts:

-- Average tokens per conversation
-- (requires adding a token_usage table or JSONB field to messages)

Recommendation: Add a token_usage JSONB column to the messages table for AI-role messages, storing { input_tokens, output_tokens, model, cost_usd }. This enables accurate cost tracking per conversation.

13. Cost Optimisation Levers

Lever	Saving	Effort
Use Haiku for orchestration (ADR-017 already plans this)	3× cheaper LLM costs	Low
Shift SMS → WhatsApp where possible	~50% per notification	Medium
Email digest for non-urgent (ADR-005)	Reduces SMS volume significantly	Medium
Prompt caching (Anthropic)	Up to 90% on repeated system prompts	Low
Context compression (ADR-018)	40-60% token reduction	Medium
BYOAK for large orgs (ADR-014)	Variable costs shift to customer	High
Batch embeddings (OpenAI Batch API)	50% off embedding costs	Low
Negotiate Twilio volume pricing	10-30% at scale	Low (just ask)
Cloudflare CDN for Supabase Storage	Reduce egress costs at scale	Low
R2 migration for large files	Eliminate egress at 3K+ properties	Medium
Read replicas (Supabase)	Delay compute upgrades	Medium
Query optimisation + DataLoader	Delay compute upgrades by 30-50%	Ongoing (partially done)
Resend Free tier	$0 email cost up to 3K emails/mo	Already available

14. Action Items

Immediate

Instrument LLM calls with token counting (add token_usage JSONB to messages table)
Set up Anthropic/OpenAI spend alerts
Decide on VAPI vs Retell (Retell is ~30% cheaper with custom telephony)
Add external_billing_id to organisations table (ADR-004)
Replace @sendgrid/mail with Resend SDK in package.json
Upgrade Supabase to Pro plan before real users

Before 500 Properties

Plan WhatsApp BSP migration: Twilio → direct Meta Cloud API (saves $0.005/msg)
Shift SMS notifications to WhatsApp where tenant is already on channel (50-70% cost reduction)
Run DB queries (section 12) against real data to validate assumptions
Get Twilio volume pricing quote
Monitor Supabase egress — plan CDN or R2 if approaching 250 GB/mo

Before 1,000 Properties

Implement direct Meta WhatsApp Business API integration
Finalise voice pricing model (tier-gated vs usage-based add-on)
Feed per-property cost into Business Model pricing — break-even is ~$1.50-2/property/mo with optimisations
Evaluate Supabase read replicas if compute is bottleneck

Before 3,000 Properties

Consider Cloudflare R2 for property-documents and issue-attachments (zero egress)
Evaluate Stripe Billing annual contract vs pay-as-you-go (£450/mo vs 0.7%)
Consider Supabase Team plan ($599/mo) only if SAML is required for Partner tier
Revisit Resend Scale ( $90/ m o) v s A ma zo n SES ($ 0.10/1K) for email at high volume

Resolved

~~Plan for Cloudflare Access 50-user cliff~~ — ZTNA will be removed when app goes public (Terraform destroys Access app + policy)
~~n8n cloud/self-hosted decision~~ — n8n is no longer required. Removed from service inventory.
~~SendGrid vs alternative~~ — Decided on Resend. Better free tier, modern DX, competitive pricing.

Note: Vercel → Cloudflare Migration

The earlier Capacity Analysis and Pricing Analysis reference Vercel as the hosting layer. The dashboard has since migrated to Cloudflare Workers via @opennextjs/cloudflare. This analysis uses the current Cloudflare pricing. Key differences:

Cloudflare Workers Paid: ** $5/ m o * * (v s V erce lP ro$ 20/mo per team member)
Includes Hyperdrive connection pooling, Pages, and DNS at no extra cost
No per-function invocation charges (included in 10M requests/mo)
Static assets are free and unlimited (not counted against request quota)

This makes hosting cheaper than the session docs estimated.

Business Model
Capacity Analysis (Session 1 — references Vercel, now on Cloudflare)
Pricing Analysis (Session 2 — competitor pricing + tier recommendations)
ADR-004 Billing Integration
ADR-005 Notification Preferences
ADR-014 White-Label & BYOAK
ADR-017 RAG Pipeline v2
ADR-018 RAG Context Management
Tech Stack

EHQ Brain

Explorer

Costs & Usage