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Firebase has two plans. Spark is free, needs no payment method, and caps each product at a daily or monthly quota. Blaze is pay as you go: it keeps the same free usage, then bills each product by its own meter, and it is required for Cloud Functions, Cloud Storage and App Hosting. Most Firebase bills come from Firestore reads, so the shape of your queries decides the cost more than the number of users.
TL;DR
- Spark is $0 with daily quotas: 50,000 Firestore reads, 20,000 writes and 20,000 deletes a day, plus 1 GiB stored.
- Blaze bills past those quotas. In Mumbai, Firestore reads cost $0.035 per 100,000 and writes $0.104. In Frankfurt they are $0.039 and $0.117.
- Cloud Functions need Blaze. 2 million invocations a month are free, then $0.40 per million, plus CPU, memory and outbound traffic.
- Auth is free up to 50,000 monthly active users. Phone sign-in bills per SMS.
- A Google Cloud budget sends alerts. It does not stop spending, so a Blaze bill has no built-in ceiling.
What is the difference between Spark and Blaze?
| Spark | Blaze | |
|---|---|---|
| Price | $0 | Pay as you go |
| Payment method | Not needed | Required |
| Free usage | Fixed quotas | Same quotas as Spark, then billed |
| Cloud Functions | No | Yes |
| Cloud Storage | No | Yes |
| App Hosting | No | Yes |
| Over the quota | The product stops until the quota resets | Billed at each product’s rate |
New Blaze accounts may be eligible for $300 of Google Cloud credit.
Spark quotas are hard limits. Firestore quotas reset daily around midnight Pacific time, so a busy afternoon in India or Europe can exhaust the day’s reads and leave the app without data until the reset.
How does Firestore pricing work?
Firestore bills per document read, write and delete, plus stored data and outbound traffic. The rate depends on where the database lives.
| Firestore location | Reads per 100K | Writes per 100K | Deletes per 100K | Storage per GiB a month |
|---|---|---|---|---|
| Mumbai (asia-south1) | $0.035 | $0.104 | $0.012 | $0.104 |
| Frankfurt (europe-west3) | $0.039 | $0.117 | $0.013 | $0.117 |
| Europe multi-region (eur3) | $0.06 | $0.18 | $0.02 | $0.18 |
| Iowa (us-central1) | $0.03 | $0.09 | $0.01 | $0.15 |
The free quota applies on both plans: 50,000 reads, 20,000 writes and 20,000 deletes a day, 1 GiB stored, and 10 GiB of outbound traffic a month. Each project gets one free database.
What counts as a read
A query bills one read for each document it returns. A screen that lists 50 items costs 50 reads every time someone opens it, so 10,000 opens a day is 500,000 reads. A query with an offset also bills a read for each document it skips, and security rules that look up other documents bill those lookups as reads too.
Real-time listeners count as well. When a document a listener is watching changes, each listening client pays a read for the update.
What is not free
Point-in-time recovery, backups, restores, clones and TTL deletes have no free usage. They need billing enabled.
How are Cloud Functions billed?
Cloud Functions run on Blaze only. Each meter has its own free amount per month:
| Meter | Free each month | Then |
|---|---|---|
| Invocations | 2 million | $0.40 per million |
| Memory time | 400,000 GB-seconds | Google Cloud rate |
| CPU time | 200,000 CPU-seconds | Google Cloud rate |
| Outbound traffic | 5 GB | $0.12 per GB |
| Cloud Build | 120 minutes a day | $0.003 per minute |
| Container storage | 500 MB | Artifact Registry rate |
Rates beyond the free amounts vary by location. Functions that wait on a slow API keep billing memory and CPU time while they wait.
What do Hosting and App Hosting cost?
Firebase Hosting serves static files and single-page apps. On Spark it includes 10 GB of storage and 360 MB of transfer a day. On Blaze, storage past 10 GB is $0.026 per GB and transfer past the daily amount is $0.15 per GB. Custom domains and SSL are included on both plans.
App Hosting is for server-rendered apps such as Next.js and Angular, and it needs Blaze. Outbound traffic is free up to 10 GiB a month, then $0.20 per GiB uncached or $0.15 per GiB cached. Storage past 5 GB is $0.10 per GB. The server code itself runs on Cloud Run and builds on Cloud Build, each billed at Google Cloud rates.
What do Auth, Storage and the Realtime Database cost?
| Product | Free | Paid |
|---|---|---|
| Authentication | 50,000 monthly active users | Google Cloud rate past that; phone sign-in bills per SMS |
| SAML and OIDC sign-in | 50 monthly active users | Google Cloud rate |
| Cloud Storage | 5 GB-months stored, 100 GB downloaded a month | Cloud Storage rates, Blaze only |
| Realtime Database | 1 GB stored, 360 MB downloaded a day, 100 connections | $5 per GB stored, $1 per GB downloaded |
The Cloud Storage free amounts only apply to buckets in us-central1, us-west1 and us-east1. A bucket in Mumbai or Frankfurt bills from the first GB.
For a relational database, Firebase SQL Connect offers a 3-month free trial of Cloud SQL for PostgreSQL, one per project. After that, Cloud SQL starts at $9.37 a month, and a project that has not moved to Blaze has its instance archived, then deleted 90 days later.
Two worked Firestore bills
Both assume a month of 30 days and a database in Mumbai, with Frankfurt alongside.
| Usage a month | Mumbai | Frankfurt |
|---|---|---|
| Small app: 6M reads, 900K writes, 2 GiB stored | about $2 | about $2.20 |
| Busy app: 30M reads, 3M writes, 5 GiB stored | about $12.90 | about $14.40 |
For the small app, the free quota covers 1.5 million reads and 600,000 writes, so 4.5 million reads and 300,000 writes bill. For the busy app, 28.5 million reads and 2.4 million writes bill, with reads making up about three quarters of the total.
These are the database lines only. Functions, Hosting traffic, Storage and SMS sign-ins add their own lines on top.
When to stay on Firebase
Stay if you are building a mobile app that uses what Firebase does best. Cloud Messaging, Crashlytics, Analytics, A/B Testing and Performance Monitoring are free. Firestore’s offline sync and real-time listeners save a lot of client code, and the Spark plan carries a small app a long way at $0.
What does the same backend cost on Ownkube?
Ownkube is a different shape. It runs your own backend and a Postgres database, billed by the resources they use rather than by reads and writes. It has no built-in auth, push notifications or client SDKs, so you bring a library for each.
| Line | Monthly cost |
|---|---|
| API at 0.25 vCPU and 0.5 GiB | $6.75 |
| Postgres on a DB 0.5 box | $4 |
| 5 GB of database storage | $1.25 |
| Total before transfer | $12 |
That total stays the same at 6 million reads or 60 million. Outbound transfer bills from the first GB at $0.02 per GB in Germany and $0.13 per GB in Mumbai, and Ownkube has no free tier, so a small Firebase app on Spark costs less.
Billing works from a prepaid wallet. Pay as you go starts with a $5 top-up, Personal is $5 a month and loads $5 of credit, and Team is $20 a month and loads $20. Credit never expires. When it runs out, apps pause and keep their data until you top up, so a runaway query loop costs at most what you loaded.
Checklist before you pick
- How many documents does your busiest screen read, and how often is it opened?
- Do you need Cloud Functions, Storage or App Hosting? All three need Blaze.
- Where are your users, and is the Firestore location close to them?
- Do you want a hard cap on spend, or are budget alerts enough?
- Would a relational database with joins fit your data better than documents?
For relational backends, Supabase pricing explained and managed Postgres pricing compare the options. Supabase vs Firebase puts the two side by side.
FAQ
Is Firebase free?
The Spark plan is free and needs no payment method. It covers 50,000 Firestore reads and 20,000 writes a day, 1 GiB of Firestore storage, Hosting with 10 GB of storage, and Auth up to 50,000 monthly active users. Cloud Functions and Cloud Storage need the paid Blaze plan.
How much does Firebase cost per month?
On Blaze, a small app often stays within the free quotas or costs a few dollars. Firestore reads in Mumbai cost $0.035 per 100,000 past the free 50,000 a day, so 30 million reads a month comes to about $10 on reads alone.
Can I set a spending limit on Firebase?
You can set a Google Cloud budget with alerts, but a budget does not cap usage. To stop spending you have to disable billing on the project or turn services off yourself.
Why is my Firestore bill so high?
Usually reads. Every document a query returns is a read, real-time listeners bill a read on each update, and security rules that look up other documents add reads. Paginating lists and caching on the client lower it.
Does Firebase charge for Cloud Functions on the free plan?
Cloud Functions are not available on Spark. On Blaze, the first 2 million invocations a month are free, then $0.40 per million plus CPU, memory and traffic.
Where Ownkube fits
If your Firebase bill grows with reads and you would rather pay for a server and a Postgres database that cost the same however many queries they serve, Ownkube runs both in Mumbai or Germany from a prepaid wallet. Deploy my first app.