Supabase vs Firebase: Monthly Cost & Read-Billing Comparison

When you launch a new app, [Firebase](https://firebase.google.com) feels practically free because Google gives you 50,000 document reads per day at $0. The trap appears when your product adds a feed, leaderboard, or dashboard that loads 30 items every time a user opens the screen. Ten thousand daily users refreshing that page five times a day trigger 1.5 million document reads daily—45 million reads per month—before counting background listeners.

With Supabase, you pay for the underlying PostgreSQL server capacity and storage ($25/month Pro base) rather than paying a toll on every single SQL query. So long as your database CPU handles the load, whether your users run 1 million or 100 million queries a month costs $0 extra.

As a B2B product matures, customers inevitably ask for filtered reports—such as joining user profiles, subscription invoices, and team permissions in a single view. Because Supabase is full PostgreSQL under the hood, you can run standard SQL joins, views, and `pgvector` similarity searches inside the exact same database.

In [Firebase](https://firebase.google.com) Firestore, data is stored as nested JSON documents. Joining two collections or filtering across multiple fields often forces developers to duplicate data across multiple folders—which in turn multiplies your write and storage bills every time a user updates their profile.

One of the biggest hidden costs in software infrastructure is rewriting your backend three years later. Because [Firebase](https://firebase.google.com) uses proprietary Google SDKs and security rules, moving off Firebase to AWS or your own servers requires rewriting almost every data-fetching function in your app.

Supabase is 100% open-source and stores your data in a standard `.sql` dump. You can move to AWS RDS, Google Cloud SQL, or a self-hosted Docker server over a weekend without rewriting your database schema.