How to cap Google Cloud billing with spend cap budgets

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Last checked 2026-10-20 (ET). Tick each step as you go. Your progress is saved in this browser only.

Google Cloud billing has two kinds of budget, and only one of them can stop spend:

Spend cap budgets pause one service in one project when estimated spend passes your amount. They only work for a short list of services.
Alerts-only budgets send emails or Pub/Sub messages but never pause anything.

Using Firebase? Its caps use the same system. Firebase spend caps. See all 9 providers.

Official docs: Manage spend cap budgets and Create, edit, or delete budgets and budget alerts

Services you can cap

Gemini API (generativelanguage.googleapis.com)
Gemini Enterprise Agent Platform, formerly Vertex AI (aiplatform.googleapis.com)
Cloud Run (run.googleapis.com)
Cloud Run functions (cloudfunctions.googleapis.com)

Create a spend cap budget

In the Google Cloud console, go to the Budgets & alerts page for your Cloud Billing account.
Click Create new budget. (You can't convert an existing alerts-only budget into a spend cap. Create a new one.)
Define: select Spend cap enforcement, enter a name, click Next.
Scope: select a single project and a single eligible service. The time range is fixed to Monthly. Click Next.
Amount: enter the target amount. Click Next.
Actions: click Finish.

You need a billing role that includes billing.budgets.configureSpendCap (billing account level) or billing.resourcebudgets.configureSpendCap (project level).

What the cap does

When gross, estimated costs for that service pass 100% of the amount, new usage of the service in that project is paused for the rest of the month.
Caps lift on their own at the start of the next budget period, or you can lift one by hand.
Alert emails go out at 50%, 80% and 100% to all billing administrators and project owners.

What it does not do

It is not instant. Google says "the enforcement of spend caps isn't instant and any cost overages are billed as normal." Set the amount a little below your true limit.
In-flight requests finish and are billed.
It doesn't pause "on-going, fixed usage associated with persistent resources (such as compute and storage services)."
One project and one service per cap. Folders, organizations, labels and multi-project or multi-service budgets are not supported.
Cost math uses list prices and excludes savings and credits.
Reseller accounts are out of scope.
"For spend cap budgets, the alerts and recipients can't be customized."

Alerts for everything else

For services you can't cap, create an alerts-only budget:

On Budgets & alerts, click Create new budget and keep Alerts only.
Set the scope and amount, and add threshold rules.
Under email notifications, you can keep Email alerts to billing admins and users, and select Link Monitoring email notification channels to this budget to send alerts to "email addresses of your choice."
Optionally connect a Pub/Sub topic to get programmatic updates several times a day.

Google's warning about alerts-only budgets: they "don't automatically prevent the use or billing of your services when the alerts-only budget amount or threshold rules are met or exceeded."

Thresholds can trigger on Actual or Forecasted spend. Google's example: "if you set a 110% forecasted cost alert on a $100 budget, then you receive an alert notification when you are forecasted to spend more than $110 by the end of the budget calendar period." Also, "Budgets configured for a custom time range cannot trigger alerts on Forecasted costs."

Google notes it "may take several hours before receiving the first email or Pub/Sub notification," and that cost data lags usage.

If you need a harder stop for other services, Google documents a pattern where a budget notification triggers your own function to disable billing on the project. Disabling billing can shut services down, so read Google's warnings first.

Where CapBrake helps

Google Cloud does not give you one hard cap on your whole bill, so alerts still matter. Use the free CapBrake checklist to tick off each step above. Your progress is saved in your browser. No account and no credentials.

CapBrake also has an alert relay for providers like Google Cloud. It is free in early access. You put a private relay address on your budget alerts, and CapBrake sends each alert to your browser or Slack. CapBrake will never ask for your Google Cloud credentials.