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How to set a monthly spend cap on the Gemini API
Enabling billing removes Google's free-tier ceiling — put a hard limit in place first, and it costs less than you'd think.
If you’re captioning more than a handful of photos at a time, you’ll eventually enable billing on the Google Cloud project behind your Gemini key. It removes the free tier’s daily ceiling and unlocks Gemini 3.1 Pro. Before you flip that switch, put a spend cap in place.
Why a spend cap, not just an alert
Budget alerts only notify you — they don’t stop usage. A monthly spend cap in Google AI Studio is a hard ceiling your key cannot spend past in a calendar month.
How to set it
- Open Google AI Studio and sign in.
- Click Dashboard, then Spend.
- Confirm the Project matches your key’s project.
- In Monthly spend cap, click Edit spend cap.
- Enter a limit — say $20.00 — and save.
Good to know: The cap is an Experimental feature for billing-enabled keys, and Google measures usage with ~10-minute latency — so set it a little below your absolute maximum. It resets on the 1st (PST).
What it actually costs
Less than most expect — a large batch on Flash is typically a few cents. For current rates, see Google’s Gemini API pricing page.
