Azure AI Speech - what happens after free tier (T0) exceeds?

Question

There is this information about Azure Speech pricing:
https://azure.microsoft.com/en-us/pricing/details/cognitive-services/speech-services/

What happens if I exceed the free tier (F0), e.g. using more than 0.5 million characters TTS per month? Will it:

1. automatically start to charge something (e.g. pay-as-you-go) OR
2. just stop working with some API errors telling me about the exceeding quota?

For "AI Language" there is a FAQ at the bottom of this page:
https://azure.microsoft.com/en-us/pricing/details/cognitive-services/language-service/

It states: "Usage is throttled if the transaction limit is reached on the Free tier. Customers cannot accrue overages on the free tier."
I want to know if it's the same for "Azure Speech"?

Answer 1

Hello Benjamin Klaus,

Welcome to Microsoft Q&A and thank you for reaching out.

When you use Azure AI Speech Services (such as Text-to-Speech, Speech-to-Text, or Speech Translation) on the Free (F0) pricing tier, Microsoft provides a limited monthly allocation. For example, with Text-to-Speech (TTS), you get up to 0.5 million characters per month at no cost. This free allocation is primarily intended for testing, development, and small-scale scenarios. As long as your usage remains within this quota, you will not incur any charges.

Once you exceed the free monthly quota, Azure will not automatically start charging you. Instead, the service will typically throttle or reject additional requests beyond the free limit. This means you might start seeing HTTP 429 (Too Many Requests) or similar API errors indicating that the quota has been exceeded. The service will stop processing further requests until the next monthly cycle resets your free quota.

If you want your application or production workload to continue functioning seamlessly beyond the free quota, you’ll need to manually switch to a paid pricing tier (S0). Once you upgrade, your usage beyond the free allocation will be billed according to the pay-as-you-go pricing listed on the Azure Speech pricing page. This ensures that your application remains available and continues processing requests without throttling.

This behavior is consistent with how other Cognitive Services, such as the Azure AI Language Service, handle their free tiers. As stated in its documentation, usage is throttled when the free tier limit is reached, and overages cannot accrue automatically. Azure Speech follows the same principle your usage will stop once you hit the free limit, and you must explicitly choose a paid tier if you want to continue without interruption.

Please refer this Speech service quotas and limits.I Hope this helps. Do let me know if you have any further queries.

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