Question 1

Is Firebase or Supabase cheaper?

Accepted Answer

It depends entirely on how your app uses the database, because the two price completely differently. Firebase's Firestore bills per operation — every document read, write and delete costs money, plus stored data and egress — so its bill scales directly with traffic. Supabase is Postgres on a flat tier: the free plan is genuinely free within its limits, and the Pro plan is a fixed monthly base that includes a generous allowance of database size, bandwidth and users, with per-unit overages only when you exceed them, and no charge per query at all. The practical result is that a small or read-light app is often cheapest on Firebase's free tier or a few dollars of Firestore usage, while a read-heavy app — anything that fetches lots of documents per user, like a feed or a dashboard — blows up Firebase's per-read bill and becomes far cheaper on Supabase's flat pricing. This calculator prices both from the same usage figures so you can see exactly where the crossover sits for your workload.

Question 2

How does Firebase Firestore billing work?

Accepted Answer

Firestore, Firebase's main database, charges for four things: document reads, document writes, document deletes, and stored data, plus network egress. Reads are the cheapest per operation and deletes cheaper still, while writes cost the most, and the danger is volume — a single screen that loads a hundred documents counts as a hundred reads every time it opens. There is a small free daily allowance for each operation type and one gigabyte of free storage, which is why hobby projects often pay nothing, but past that everything is metered. Because the bill is driven by operation count rather than a flat fee, Firestore is extremely cheap at low traffic and can become surprisingly expensive at scale if your data model forces many reads per user action. This calculator applies the free daily allowances on a monthly basis and then meters the rest, so the Firebase figure reflects what you would actually be billed.

Question 3

When does Supabase become cheaper than Firebase?

Accepted Answer

Supabase wins as soon as your read volume is high enough that Firestore's per-read charges exceed Supabase's flat tier. Because Supabase does not bill per query — you pay a fixed monthly base and only pay extra for database size, bandwidth or active users beyond the included allowance — a read-heavy app pays the same whether it serves ten thousand or ten million queries, as long as the data and bandwidth fit the tier. Firebase, by contrast, keeps charging for every one of those reads. The crossover is usually reached fast for feed-style or dashboard apps that fetch many documents per view; for write-light, low-traffic apps Firebase's free tier or a few dollars of usage stays cheaper than paying for a Supabase plan. The tool marks which side is cheaper at your numbers and by how much, so you can see whether you are before or after the crossover.

Question 4

Does this calculator include every cost of each platform?

Accepted Answer

No — it models the core, comparable costs so you get an honest apples-to-apples figure, but real bills include extras on both sides. On Firebase these include Cloud Functions invocations, Authentication beyond the free tier, hosting and other Google Cloud services your app touches. On Supabase they include additional compute add-ons for heavier Postgres workloads, extra read replicas, and paid storage or edge-function usage beyond the included amounts. Pricing on both platforms also changes over time, so treat these figures as reference estimates rather than a quote, and confirm the current rates on each provider's pricing page before committing. The value of the calculator is the shape of the comparison — per-operation versus flat-tier — which is what actually decides the winner for a given workload, not the last cent of the bill.

Firebase vs Supabase Cost Calculator

Cost breakdown

Per-operation vs flat tier — that is the whole decision

How this calculator works