This document contains the current API restrictions and usage limits for Cloud Speech-to-Text. This page will be updated to reflect any changes to these restrictions and usage limits. We reserve the right to change these limits.
After submitting your request, Google may contact you for more information, and inform you whether your request is approved or denied.
Content to Speech-to-Text is provided as audio data, either directly within
content field of the request or referenced within a Google Cloud Storage
URI in the
uri field of the request. There is a limit of 10 MB on all single
requests sent to the API using local files. In the case of the
methods, this limit applies to the size of the request sent. In the case of the
method, the 10 MB limit applies to both the initial
and the size of each individual message in the stream. Exceeding this limit will
throw an error. There is no size limit on requests sent using audio data stored
in a Google Cloud Storage bucket.
The API contains the following limits on the size of this content (and are subject to change).
|Content Limit||Audio Length|
|Synchronous Requests||~1 Minute|
|Asynchronous Requests||~480 Minutes*|
|Streaming Requests||~5 Minutes**|
StreamingRecognize requests, audio must be sent at a rate that
approximates real time.
Within any request, you may also supply a PhraseSet resource containing a list of phrases specific to the request. (A single word counts as a phrase in this context.) The following limits apply to such a context:
|Speech Adaptation Limit||Value|
|Phrases per request||5000|
|Total characters per request||100,000|
|Characters per phrase||100|
The current API usage limits for Speech-to-Text are as follows (and are subject to change):
|Type of Limit||Usage Limit|
|Requests per 60 seconds*||900|
|Processing per day||480 hours of audio|
StreamingRecognize session is considered a single request even though
it includes multiple frames of
StreamingRecognizeRequest audio within the
These limits apply to each Speech-to-Text developer project, and are shared across all applications and IP addresses using a given a developer project.