The complete guide to Firebase reads (why your bill is so high)
Why is your Firebase bill so high? A complete guide to Firestore reads: how billing works, what makes reads spike, and how to find the costly ones.
Inside this guide
- Firestore bills per document read, not per query — every document a query returns is one read, and a query that returns nothing still costs one.
- Bills spike from a small number of causes: unbounded listeners, N+1 reads, fan-out, a re-rendering tile, an ingest path, and overnight machine jobs. Usually one of them dwarfs the rest.
- The Firebase console and Query Insights show you totals and slow queries — never which feature or which user spent the reads. That attribution is the whole job.