Quotas & Limits

This document contains current API restrictions and usage limits on use of the Speech API. This page will be updated to reflect any changes to these restrictions and usage limits. We reserve the right to change these limits.

Content Limits

Content to the Speech API is provided as audio data, either directly within the content field of the request or referenced within a Google Cloud Storage URI in the uri field of the request.

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 ~180 Minutes*
Streaming Requests ~1 Minute

* Audio longer than ~1 minute must use the uri field to reference an audio file in Google Cloud Storage.

For StreamingRecognize requests, audio must be sent at a rate that approximates real time.

Attempting to process content in excess of these content limits will produce an error.

Within any request, you may also supply a SpeechContext, containing a list of phrases specific to the request. (A single words counts as a phrase in this context.) The following limits apply to such a context:

SpeechContext Limit Value
Phrases per request 500
Total characters per request 10,000
Characters per phrase 100

Request Limits

The current API usage limits for the Cloud Speech API are as follows (and are subject to change):

Type of Limit Usage Limit
Requests per 100 seconds* 500
Processing per 100 seconds 10,800 seconds of audio
Processing per day 480 hours of audio

* Each StreamingRecognize session is considered a single request even though it includes multiple frames of StreamingRecognizeRequest audio within the stream.

Requests and/or attempts at audio processing in excess of these limits will produce an error.

These limits apply to each Cloud Speech API developer project, and are shared across all applications and IP addresses using a given a developer project.

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Google Cloud Speech API Documentation