Can Azure OpenAI enforce a hard spending limit or monthly budget cap?

Question

I plan to use Azure OpenAI (GPT-4o/GPT-4o mini) and text-embedding-3-large in my application. My client requires strict cost control so that AI requests stop automatically once a defined spending threshold is reached.
I understand Azure OpenAI provides TPM and RPM quotas, which control request rate, but not total monthly spend. Could you please clarify:

What happens when TPM or RPM limits are exceeded (throttling vs blocking)?

1. Any supported way to enforce a hard, service-level spending or budget cap specifically for Azure OpenAI, independent of the subscription budget?
2. For the East US region, is any free Azure OpenAI quota available? What happens after it is exhausted? Are requests blocked automatically, and is billing required to continue?

Any official guidance or best practices for enforcing strict cost limits will be helpful.
Thank you.

Answer 1

Hi Sunil Ferro

you're looking to manage costs effectively while using Azure OpenAI. Here’s a breakdown of your questions:

Throttling vs Blocking when Exceeding TPM or RPM Limits: If you exceed the Tokens Per Minute (TPM) or Requests Per Minute (RPM) limits, Azure will throttle your requests rather than blocking them outright. This means that while your requests may be delayed, they won’t be completely stopped, allowing you to continue usage within certain capacity limits.

Enforcing a Hard Spending Limit: Currently, Azure OpenAI does not provide a way to enforce a direct spending limit independent of the subscription budget. However, you can set a budget through the Azure portal which includes notifications for when you approach your budgeting threshold. This won't automatically stop services but can help you monitor and respond to spending.

Free Quota in East US Region: There is generally no standard free quota for Azure OpenAI services beyond the initial credits granted to new users. Once these credits are exhausted, requests will be blocked until you either add a payment method or upgrade your subscription. You will receive email notifications when nearing your limits, and continuing to use the services after exhausting free quotas will require billing.

For best practices:

• Create a Budget: You can create a budget in the Azure portal to track your spending. Here’s how you can set it up:
  • Go to Cost Management + Billing in the Azure portal
    • Find your subscription and go to the Budgets section
      • Click on Add to create a new budget, defining the limit and time period
        • Set up notifications for when you reach certain thresholds.

Feel free to explore these resources for more detailed steps and policies:

• Azure OpenAI Pricing
• Plan to Manage Costs for Azure OpenAI
• Create and Manage Budgets in Azure

I Hope this helps. Do let me know if you have any further queries.

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Thank you!

Answer 2

Azure OpenAI does not provide a built-in mechanism to enforce a hard spending limit or monthly budget cap independent of the subscription budget. The quotas for Tokens-Per-Minute (TPM) and Requests-Per-Minute (RPM) control the request rate but do not directly correlate to total monthly spending. When these limits are exceeded, throttling occurs, meaning that requests will be delayed until the rate falls back within the allowed limits, rather than being blocked outright.

1. Currently, there is no supported way to enforce a hard, service-level spending or budget cap specifically for Azure OpenAI beyond managing your TPM and RPM quotas.
2. In the East US region, Azure OpenAI does provide some free quota. Once this free quota is exhausted, requests will be blocked automatically, and billing will be required to continue using the service. You would need to manage your usage to stay within the free tier or be prepared for charges once it is exceeded.

For best practices, it is advisable to monitor your usage closely and consider implementing your own logic in your application to halt requests when a certain spending threshold is approached. This can help ensure that you stay within desired budget limits.

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References:

• Manage Azure OpenAI in Azure AI Foundry Models quota
• Azure OpenAI in Microsoft Foundry Models quotas and limits