Supabase vs Firebase vs PlanetScale: The Real Database Cost Breakdown

By: Trove Deck Solution Date: 2026-06-11 Reading time: 7 min

A solo founder shipped a side-project MVP on Firestore in January 2025. By March, the read-heavy dashboard was pulling 4.2 million reads per day. The Firebase bill hit $387/month — before a single paying customer. He migrated to Supabase in a weekend and cut the bill to $25. Same data, same features, one-tenth the cost.

This is the database cost trap nobody warns you about at hackathons. Choosing a backend isn’t about which logo looks cooler — it’s about how your specific access pattern maps to a pricing model. Let’s look at the three most popular options for indie builders and break down what you actually pay.

What is Supabase, Firebase, and PlanetScale?

These are three distinct approaches to backing your SaaS with a managed database, each optimized for a different workload philosophy.

Supabase is an open-source Firebase alternative built on PostgreSQL. You get a full relational database, auth, real-time subscriptions, storage, and Edge Functions. Pricing is flat-rate per tier: Free (500 MB, 50K MAU), Pro at $25/month (8 GB, 100K MAU), Team at $599/month. You pay for database size and bandwidth, not per read.

Firebase (Firestore) is Google’s NoSQL document database. It’s serverless by default — no connection pooling, no server management. Pricing is pure pay-as-you-go: $0.18/GB storage, $0.06 per 100K reads, $0.12 per 100K writes. A Blaze plan minimum kicks in at $25/month.

PlanetScale is a MySQL-compatible serverless database built on Vitess. Its killer feature is branching — branch your schema like Git branches. Hobby tier: 1 GB free. Scaler: $39/month (10 GB, 10B row reads). Scaler Pro: $99/month. Enterprise: custom.

The Cost at Three User Tiers

Here’s the math that matters. Assume a typical B2B SaaS with moderate read/write ratios: each active user generates roughly 200 reads and 20 writes per session, 3 sessions per day.

At 1,000 users, PlanetScale is the most expensive option — you’re paying $39/month for capacity you don’t need. Firebase looks cheapest thanks to generous read quotas on the free tier. Supabase sits in the middle at $25 if you exceed the free tier.

The story flips at 100,000 users. Firebase’s per-read pricing compounds fast. A dashboard that auto-refreshes every 30 seconds adds tens of thousands of reads per user per day. PlanetScale caps at $99/month with predictable row-read limits. Supabase stays flat unless your data volume outgrows the tier.

Firebase’s Hidden Cost: The Read Multiplier

Firestore charges per document read, not per query. Fetching a list of 10 items reads 10 documents. If you have a nested document structure — say, users → projects → tasks — a single “load my tasks” action can read 50+ documents. Multiply that by 100K users hitting a real-time dashboard, and your bill explodes.

The fix exists (denormalize aggressively, use composite queries, cache with Redis), but it requires architecture discipline that most solo founders don’t have time for at MVP stage. You’re essentially optimizing your data model to serve the pricing model, not the product.

Unlike Supabase and PlanetScale, Firebase doesn’t give you a relational query planner. You can’t JOIN. You can’t do complex aggregations without Cloud Functions, which incur separate billing. Every Cloud Function invocation that reads Firestore triggers another round of document reads.

When Supabase Wins (and When It Doesn’t)

Supabase shines for founders who think in SQL. You get full PostgreSQL — JOINs, CTEs, window functions, extensions like PostGIS and pgvector. Row-Level Security policies live in the database, not application code. The $25 Pro tier covers most solo-SaaS workloads through 100K users.

One client we worked with at Trove Deck Solution ran a real-time analytics dashboard backed by Supabase. Their pattern: heavy writes (event ingestion), moderate reads (aggregated views). Supabase handled it on the Pro tier without issue, because the pricing model doesn’t penalize write volume the same way Firestore does.

Where Supabase stumbles: connection limits. The free tier caps at 60 concurrent connections. Pro tier adds more, but if you’re running a background job worker that opens persistent connections, you’ll hit the ceiling. The fix is PgBouncer (Supabase supports it), but it adds a layer of operational complexity.

Also, Supabase’s edge functions run on Deno, not Node.js. If your backend logic depends on a specific npm package ecosystem, you’ll hit friction.

PlanetScale: The Branching Premium

PlanetScale’s schema branching is genuinely unique. You can run two versions of your database schema in parallel, test migrations against production traffic patterns, and merge when confident. For teams iterating on data models weekly, this is worth the premium.

The trade-off: PlanetScale dropped foreign key support in 2024 for its serverless tiers (they recommend application-level referential integrity). If your schema has deep relational dependencies enforced at the database level, this is a dealbreaker. You’re also locked into MySQL syntax — no Postgres extensions, no JSON operators as flexible as Postgres’s.

At the $39 Scaler tier, you get 10 billion row reads per month. For most SaaS apps at 10K–50K MAU, that’s plenty. The $99 Scaler Pro tier effectively gives you unlimited reads and writes. The cost curve is the flattest of the three.

Five-Step Decision Framework

1. Map your read/write ratio. If reads outnumber writes by 50:1 or more, avoid Firestore unless you budget for denormalization work.
2. Count your concurrent connections. If you run background workers or long-polling, Supabase’s connection limits matter. PlanetScale’s serverless model avoids this.
3. Estimate data growth. If you’ll exceed 10 GB within 6 months, Supabase’s tier jumps get steep ($599 for Team). PlanetScale’s Scaler Pro at $99 is more forgiving.
4. Evaluate query complexity. Need JOINs, aggregations, or geospatial queries? Supabase on Postgres is the clear winner. Firestore requires workarounds.
5. Factor in migration cost. Moving off Firebase means rewriting your entire data access layer. Moving between Supabase and PlanetScale means porting SQL dialects. Choose your lock-in level deliberately.

What Most Founders Get Wrong

The biggest mistake is optimizing for the free tier instead of the 100K-user tier. Free tiers are marketing tools. They’re designed to get your data in, not to be your production infrastructure.

A secondary mistake: ignoring egress costs. All three providers charge for bandwidth beyond their free tiers. Supabase includes 250 GB bandwidth on Pro. Firebase includes 1 GB/day free, then $0.12/GB. PlanetScale includes varying amounts by tier. If your app serves large payloads — think image-heavy dashboards or CSV exports — egress can exceed your database compute cost.

Third mistake: assuming “serverless” means “no ops.” All three require monitoring. Firebase needs read/write budgeting. Supabase needs connection pool tuning. PlanetScale needs schema migration discipline. The ops burden just shifts form — it doesn’t disappear.

The Bottom Line

For most solo SaaS founders building a conventional web app with relational data, Supabase at $25/month is the best value. You get Postgres, auth, real-time, and storage in one bill. The pricing model rewards you for writing efficient SQL, which is a skill worth building anyway.

Firebase is the right call only if your app is inherently real-time collaborative (chat, multiplayer, live dashboards) and you’re willing to invest in denormalization. PlanetScale is worth the premium if schema iteration speed is your bottleneck and you’re comfortable with MySQL.

Whichever you choose, run the cost projection at your target user count before you write a line of code. The database you pick on day one will be the one you’re migrating from on day 400.

Building a custom SaaS and not sure which database stack fits your architecture? The team at Trove Deck Solution has shipped production apps on all three platforms and can help you run the numbers for your specific use case.

#SaaS#IndieHackers#Supabase#Firebase#PlanetScale#DatabaseCosts#TechStack#SoloFounder