The Brutal Truth About Firebase Costs (and How I Kept My Bill at $5)
When I first started using Firebase, I thought I had found the perfect tool. It was easy, it was fast, and it said “free.”
But then I discovered something many developers learn the hard way: Firebase can quietly become very expensive. Some developers wake up to hundreds of dollars in surprise bills just because of how they set it up. Firebase is powerful, but if you don’t understand how pricing works, it can drain your budget.
The good news? I’ve been running an online store with hundreads of users and my Firebase bill is still only $5 per month. Here’s how.
Why Firebase Can Get Expensive
Firebase charges you based on usage, not a flat monthly fee. That means your costs depend on how your app behaves.
Real-time updates
The most dangerous feature is real-time listeners. Here’s why:
Imagine 100 users looking at a list of 100 products. Every time something changes, Firebase “reads” those 100 documents for each user. That’s 10,000 reads per second. Which equals about $15 per hour. Run that setup for a day, and you could easily spend hundreds.
File storage
Storing files like images is cheap. The real cost comes from downloads. If users are constantly loading large product images, your bill climbs quickly.
Authentication
Firebase Auth gives you 50,000 monthly active users for free. That’s generous. But once you cross that line, you start paying per user. If you’re not ready, that can feel like a sudden jump.
How I Keep My Costs Low
Here are the simple choices I made:
- I don’t use real-time updates everywhere. Data only refreshes when users request it.
- I compress and resize images before uploading them. That way, users aren’t constantly downloading huge files.
- I host my website on Firebase Hosting, which is free and comes with a global CDN.
- I designed my database to keep queries simple, so each product equals one read.
- I only use cloud functions for short tasks, like confirming an order.
My Actual Monthly Costs
With around 500 to 700 users a month, here’s what I pay:
- Hosting: $0
- Authentication: $0
- Database reads/writes: about $2–3
- File storage: about $1–2
- Notifications: $0
Total: about $5 per month. That’s cheaper than one fast-food meal.
What If I Outgrow Firebase?
If my app keeps growing, at some point Firebase will no longer be the cheapest option. When that happens, I can:
- Move to Supabase, which uses a traditional Postgres database.
- Try AWS Amplify, which is more flexible but harder to learn.
- Or set up my own server for complete control, though that requires more work.
The point is, Firebase is great for starting and scaling to a decent size. Beyond that, you have options.
The Bottom Line
Firebase isn’t expensive if you know how to use it. It only becomes expensive when you turn on features you don’t need. If you’re starting out, remember these rules:
- Don’t use real-time updates for everything.
- Keep images small and optimized.
- Design your database with simple queries in mind.
- Check your usage regularly.