This guide provides an overview of different Gemini API billing options, explains how to enable billing and monitor usage, and provides answers to frequently asked questions (FAQs) about billing.
About billing and tiers
Billing for the Gemini API is based on your payment history.
| Usage tier | Qualification | Billing tier cap |
|---|---|---|
| Free | Active project or free trial | N/A |
| Tier 1 | Set up and link an active billing account | $250 |
| Tier 2 | Paid $100 + 3 days from first successful payment | $2,000 |
| Tier 3 | Paid $1,000 + 30 days from first successful payment | $20,000 - $100,000+ |
New accounts begin on the Free Tier, which allows access to certain models in the Gemini API and AI Studio, up to the models' free tier rate limits.
To deploy your applications directly from Build mode, you can use the Google Cloud Starter Tier. This tier lets you publish up to 2 full stack applications without setting up a Google Cloud project or billing account. See Deploying from Google AI Studio for details and refer to the Google Cloud Starter Tier documentation for more information.
To access higher rate limits, use advanced models, and ensure your prompts and responses are not used to improve Google products*, you can link a billing account and Prepay to move to the Paid Tiers. Then, you'll move through higher tiers based on cumulative spend and account age.
Tiers, rate limits, and billing account caps are all determined at the billing account level.
* Enterprise-grade data privacy: For more information on data use for paid services, see the Terms of Service.
Set up billing to access the Paid Tier
You can create a project and set up billing, or import an existing project, to upgrade to the Paid Tier in Google AI Studio. Upgrading from the Free Tier to the Paid Tier means linking a billing account and prepaying to add a minimum of $5 (or equivalent in other currencies) of credits to your account.
- Go to the AI Studio API keys page,
Projects page, or anywhere you see
Set up billing button in AI Studio.
- New users will have a project and API key created for them by default.
- If you need a new key, click Create API key and follow the dialog to add a key-project pair to the table.
- Find the Free Tier project you want to upgrade to the Paid Tier, and click Set up billing under the Billing Tier column.
- If you've never set up a Google billing account before:
- You'll be asked to select your country to agree to the Terms of Service.
- Then, fill in or confirm your contact information and payment method to continue.
- If you have set up Google billing accounts in the past:
- You'll be asked to choose from your existing billing accounts.
- If you don't want to use any of your existing accounts, click Add new billing account and fill in or confirm your contact information and payment method to continue.
- Next, you will either be:
- Asked to prepay a minimum of $5 to complete billing setup (meaning your account is auto-assigned to the Prepay billing plan),
- Given the choice between Prepay and Postpay billing plans for your account.
- Assigned to a Postpay billing plan for an intermediary period until the new Prepay system propagates to all users (starting March 23, 2026).
- After prepaying or selecting Postpay, your account setup is complete.
Upgrade to the next paid tier
If you're already on a paid tier and meet the criteria for a plan change, you will be automatically upgraded to the next tier (subject to processing times).
Verify billing status
After you have linked a billing account to your project, you can monitor its status on the AI Studio Billing page. Unlike the free tier, paid tier status is dynamic; while your usage tier is determined by your account history, the Gemini API will only serve requests if you have a positive Prepay credit balance.
On the Projects page, you'll be able to see your project's tier and billing plan under the Billing Tier column. Any billing status actions you may need to take for a project display in the Billing Tier or Status columns:
- "Set up billing" if the project doesn't have a billing account attached.
- "Set up Prepay" if the project does have a billing account attached, but is required to use a Prepay billing plan that needs to be set up.
- "No credits" if the billing account is required to purchase credits but the Prepay payments account isn't set up or the available credit balance is depleted.
Click any of the messages to proceed with the necessary actions.
Monitor usage
You can monitor your usage of the Gemini API in Google AI Studio in Dashboard > Usage.
Billing plans
Billing plans for the Gemini API and AI Studio fall into two categories that determine when you pay for usage: Prepay and Postpay. You can check your assigned billing plan and manage payment methods on the AI Studio Billing page.
Prepay
In the Prepay billing plan, you purchase credits towards your prepay balance in advance of your Gemini API usage, and your API usage costs are deducted from your Prepay credit balance in near real-time. You can prepay by adding credits into your account, or setting up auto-reload. After credits are purchased, unused credits expire after 12 months and are non-refundable, except after switching to a Postpay account.
When your Prepay credit balance on the billing account hits $0, all API keys in all projects linked to that billing account will stop working simultaneously. Prepay credits apply only to Gemini API usage costs; you can't use them to pay for other Google Cloud services.
New users default to the Prepay billing plan. Projects that pre-date the introduction of Prepay and Postpay billing plans may need to update their project's billing details before continuing to use the Gemini API.
Note that Prepay is not available for Invoiced (or Offline) accounts.
Add Prepay to an existing Postpay account
If your existing Cloud Billing account uses a Postpay plan, you can add Prepay capabilities to purchase credits in advance. These prepay credits let you use the Gemini API without creating a new Cloud Billing account.
During the setup to add Prepay to an existing account, you are presented with a mandatory confirmation screen explaining that your selected Cloud Billing account will be modified.
The system must modify your account state before you submit your prepayment. Therefore, canceling the process after confirming the modification but before completing the prepayment setup might result in temporary service disruptions for projects already linked to that Cloud Billing account. Ensure you are ready to complete the prepayment process before confirming the transition. If you encounter issues, see Services disrupted after canceling a Prepay setup.
If you are eligible and manually switch from a Prepay cycle to a Postpay cycle, any remaining prepay credit balance is automatically refunded to the original payment method used for the prepayment. However, if you close your Cloud Billing account for any other reason, any remaining prepay credits are forfeited and aren't refunded.
Buy credits
You can manually purchase credits in advance of your Gemini API usage to load them into your Prepay account credit balance.
To purchase credits, go to the AI Studio Billing page and select Buy credits. The minimum purchase is $5. The maximum amount of credits you can prepay for is $5,000.
Auto reload
Auto-reload is an optional feature that automatically tops up your Prepay credit balance when it's running low. This is useful to prevent service interruptions.
You can set up auto reload and see your auto-reload status in the Available credits card on the AI Studio Billing page. Click Setup auto-reload or Manage auto-reload to set your payment method, reload amount, and the minimum balance that triggers a reload payment.
Monthly auto-charge limit
The monthly auto-charge limit is available to Prepay users and helps prevent unexpected costs from frequent automatic credit reloads. Use this feature to set a maximum limit for automatic credit reloads within a single billing cycle. Once the total amount of automatic reloads in a billing cycle reaches this limit, the system disables auto-reload until the start of the next month. One-time payments you initiate manually don't count against this limit.
To set the monthly auto-charge limit when auto-reload is enabled:
- Go to the AI Studio Billing page.
- Click Manage auto-reload.
- Expand the Monthly Limit section and enter the maximum monthly limit for auto-reloads.
- Click Save.
Postpay
In the Postpay billing plan, your Cloud Billing account accrues costs and you are automatically charged at the end of the month, or when your costs reach an automatically assigned spend cap based on your account tier. The payment is charged to the payment method attached to your Postpay payments account, which you can manage on the AI Studio Billing page. On the Billing page you'll be able to view your balance, due dates, and past payments, as well as make payments and manage payment methods.
When setting up billing for a new project, if you are eligible for Postpay, you will have the option to choose between Prepay and Postpay in the billing setup dialogue.
After you switch a Cloud Billing account to use the Postpay billing plan, all projects linked to that billing account are switched to the Postpay plan. You can move an eligible account to Prepay by following the steps in Migrate to prepay. You can also move a project to a billing account with a different billing plan to change the charging cycle for that project; visit the Cloud documentation on managing billing for projects.
You can learn more about the Postpay charging cycle in the Cloud Billing guide.
Migrate to prepay
Google AI Studio is transitioning developer accounts from Postpay to Prepay billing for Gemini API usage. This change applies only to the Gemini API; other Google Cloud services linked to your billing account remain on Postpay.
Switch to Prepay and add credits before the cutover date in your account notice to avoid service interruptions. Accounts that use only Free Tier features do not need to take action.
To switch an existing Postpay account to Prepay:
- Go to the AI Studio Billing page.
- Select Switch to Prepay for your billing account.
- Purchase credits (minimum $5) to load your starting balance.
To prevent service interruptions after switching, configure auto-reload to top up your credit balance when it runs low.
Spend caps
The Gemini API supports monthly spend caps at both the billing account tier and project levels. These controls are designed to protect your account from unexpected overages, and the ecosystem to ensure service availability.
Note that spend caps are not available for Invoiced (or Offline) accounts.