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Supabase vs Firebase for a SaaS comes down to how the bill grows. In our worked example, an app with 100,000 monthly active users costs about $125 a month on Supabase Pro and about $391 on Firebase, because Firestore bills every read and Firebase Auth charges past 50,000 users. Below 10,000 users, Firebase is cheaper.
Most comparisons stop at “SQL vs NoSQL” and tell you to run the calculators. This one runs them, with the assumptions written down so you can swap in your own, then prices the part nobody bills you for up front: leaving.
Supabase vs Firebase: the worked bill
Assume a B2B SaaS where each monthly active user triggers 3,000 database reads and 300 writes a month, about 100 reads a day. We count auth, database operations and the base plan, and leave out file storage and egress, which both platforms bill on top. All prices are from the vendors’ own pages as of 13 October 2026.
| Monthly active users | Supabase | Firebase (Blaze) |
|---|---|---|
| 1,000 | $25 (Pro, Micro compute) | Under $1 |
| 10,000 | $30 (Pro, Small compute) | About $11 |
| 100,000 | $125 (Pro, Large compute) | About $391 |
How the Supabase column works. Supabase’s pricing page lists Pro at $25 a month with 100,000 MAUs, an 8 GB database and 250 GB of egress included, plus $10 of compute credit that covers a Micro instance. Bigger instances cost the difference: Small is $15, Medium $60, Large $110 a month. Past 100,000 users, auth is $0.00325 per MAU. The compute sizes in the table are our assumption for this read load; yours depends on query patterns more than user count.
How the Firebase column works. Firestore’s free tier is 50,000 reads and 20,000 writes a day. Past that, Google Cloud’s Firestore pricing for us-central1 is $0.03 per 100,000 reads and $0.09 per 100,000 writes. At 100,000 users that’s about $90 in reads and $26 in writes. Auth adds the rest: Firebase lists Authentication with Identity Platform as free to 50,000 MAUs, and Identity Platform pricing charges $0.0055 per MAU from 50,000 to 100,000. That’s $275 for the second 50,000 users.
The free Supabase plan would cover the 1,000-user row on paper, but free projects pause after a week of inactivity, so we price production on Pro.
Firestore bills reads, so code decides cost
Supabase charges for the machine. Firestore charges for what your code does. A dashboard that re-reads 50 documents on every page load, or a listener attached to a whole collection, can multiply reads per user by ten. In our example that alone moves the 100,000-user read bill from about $90 to about $900, with no change in users.
Firebase won’t stop that for you. Its guide to avoiding surprise bills says plainly that “budget alerts do not pause services”. Spend caps that do pause a service exist only for AI Logic, App Hosting, Cloud Functions and Extensions, so Firestore isn’t covered. Supabase’s Spend Cap blocks overage on egress, MAUs, disk size and Realtime, though compute keeps billing because you chose the instance size.
Supabase has its own cost traps: compute upgrades, $100 a month per 7 days of point-in-time recovery, and egress at $0.09 per GB past 250 GB. They’re priced per resource, so they show up in a forecast before they show up on an invoice. If you’re already on Supabase, our guide to Supabase row level security not working covers the access bugs that cost more than any of these.
Leaving Firestore costs more than leaving Postgres
Lock-in is a bill you pay once, on the way out.
Leaving Supabase. The database is Postgres. Supabase’s own guide to moving from the platform to self-hosted is three supabase db dump commands (roles, schema, data) and a psql restore. The same dump loads into any managed Postgres. Auth, storage and edge functions need rework if you leave Supabase entirely, but your tables, constraints and queries come with you unchanged.
Leaving Firebase. Firestore’s managed export needs the Blaze plan and writes files to a Cloud Storage bucket. The docs cover importing them into another Firestore database or loading them into BigQuery; there’s no documented path to Postgres. To land in Postgres, you write the transform yourself: flatten nested documents, design the tables and foreign keys Firestore never enforced, and backfill. Users move more easily. Supabase’s Firebase Auth migration tools export users to JSON and import them, using the scrypt hash parameters from your Firebase console.
The same holds when you leave Bubble: the data model is the slow part. Our guide to migrate a Bubble app to Supabase walks through it, including moving users without password resets.
Where Firebase still wins
Firebase is the better pick for mobile-first apps that work offline. Firestore’s offline persistence is on by default for Android and Apple apps, caching the data the app is using and syncing writes on reconnect. Supabase leaves offline sync to you.
The SQL argument is also weaker than it was. On 22 April 2026, Firebase renamed Data Connect to SQL Connect and added realtime sync, an offline cache and native SQL, all on Cloud SQL for PostgreSQL. The Firebase pricing page lists a three-month no-cost trial, then Cloud SQL from $9.37 a month and $0.90 per million operations past 250,000. If your team is committed to Google Cloud and wants Postgres, you can now stay inside Firebase.
When your own backend is the rational choice
Roll your own when the service is the problem, not the price. Three cases:
- A compliance or residency rule neither vendor meets. If a customer contract names a region, a cloud or an audit regime Supabase and Firebase can’t sign up to, you run Postgres yourself.
- A workload neither hosts well. Long-running jobs, heavy background processing or a database that has to sit next to other systems in your own cloud account.
- A team that can run it. Your own backend means you own auth, backups, upgrades and on-call. Without a senior engineer for that, the savings vanish in the first incident.
Self-hosted Supabase is the cheaper middle step: same SDK, same Postgres, your servers. Our Bubble vs Webflow vs custom code comparison makes the same point one level up: move down the stack only when the layer above stops you shipping.
How to choose between Supabase, Firebase and DIY
- Relational B2B SaaS on the web: Supabase. Predictable per-resource pricing, and the exit is a Postgres dump.
- Mobile-first consumer app that must work offline: Firebase with Firestore. Budget per read and test listener patterns before launch.
- Already on Google Cloud and want SQL: Firebase SQL Connect on Cloud SQL.
- Under 10,000 users and testing an idea: either. Firebase is cheaper, but choose by the exit you want later.
- Past 50,000 users on Firebase Auth: price the move now; auth fees start there.
- A contract or workload neither vendor meets: your own Postgres, ideally starting from self-hosted Supabase.
What Sam’s List and 100+ audits show us
Our audit case studies cover more than 100 applications across security and performance, with clients including Sam’s List, VoiceDrop and AppSheet Training. We specialize in Bubble and Supabase apps, where the abstraction layers hide the problems scanners miss. On Supabase, the audits test auth flows, data exposure, access control and database queries by reading the policies and SQL directly. That transparency is why we reach for Supabase on most SaaS MVPs: when something is wrong, the cause is in Postgres where you can see it and fix it.
If you’re choosing a backend for a new product, our MVP development sprint sets up auth, payments and row-level access on day one. If a vibe-coded app is already live on one of these and misbehaving, Code Rescue is the faster route.
Frequently asked questions
- Is Supabase cheaper than Firebase?
- Not at first. In our worked example, Firebase costs under $1 a month at 1,000 users against $25 for Supabase Pro. The lines cross near 10,000 users, and at 100,000 users the same app costs about $125 a month on Supabase and about $391 on Firebase, mostly from Firestore reads and Firebase Auth fees past 50,000 users.
- Does Firebase have a spending limit?
- Not for Firestore. Firebase budget alerts send emails but do not pause services. Spend cap budgets that pause a service exist only for Firebase AI Logic, App Hosting, Cloud Functions and Extensions. Supabase Pro has a spend cap that blocks usage past quota for items like egress and MAUs, though compute is still billed.
- How hard is it to migrate from Firebase to Supabase?
- The data is the hard part. Firestore's managed export writes files that only import into another Firestore database or BigQuery, so you write your own transform into Postgres tables. Users move with Supabase's firebase-to-supabase scripts, which take your Firebase password hash parameters. Plan schema design and a parallel run before cutover.
- Can Firebase use PostgreSQL now?
- Yes. Firebase Data Connect, renamed SQL Connect in April 2026, runs on Cloud SQL for PostgreSQL and added realtime sync, an offline cache and native SQL queries. It has a three-month no-cost trial for the first instance, then Cloud SQL from $9.37 a month plus $0.90 per million operations past the free 250,000.
- When should a SaaS build its own backend instead of using Supabase or Firebase?
- When a vendor limit blocks you, which the bill alone rarely does. That means a compliance or data residency rule neither vendor meets, a workload neither hosts, or a team ready to run Postgres, auth and storage itself. Self-hosted Supabase is the cheaper middle step, because the database moves with a dump and restore.
References
- Supabase - Pricing
- Firebase - Pricing plans
- Google Cloud - Firestore Standard edition pricing
- Google Cloud - Identity Platform pricing
- Firebase - Avoid surprise bills
- Supabase - Cost control and the Spend Cap
- Firebase - Export and import Firestore data
- Supabase - Transferring from platform to self-hosted Supabase
- Supabase - Migrate from Firebase Auth to Supabase
- Firebase - What's new from Firebase at Cloud Next 2026 (April 22, 2026)
- Firebase - Access Firestore data offline
Khushi Arora