Guidelines and quotas - Amazon Transcribe

Guidelines and quotas

Amazon Transcribe has several guidelines to follow in order to achieve optimal results. There are also quotas that may impact your transcriptions; some of these can be increased. Refer to the following sections for details.

Supported AWS Regions

For a list of AWS Regions where Amazon Transcribe is available, see Amazon Transcribe Endpoints and Quotas in the AWS General Reference.


For best results:

  • Use a lossless format, such as FLAC or WAV with PCM 16-bit encoding.

  • Use a sample rate of 8,000 Hz for low-fidelity audio and 16,000-48,000 Hz for high-fidelity audio.

If you don't need to process all of your transcription jobs concurrently, use Job queueing. This enables Amazon Transcribe to keep track of your transcription jobs and process them when slots are available.


Amazon Transcribe may temporarily store your content to continuously improve the quality of its analysis models. See the Amazon Transcribe FAQ to learn more. To request the deletion of content that may have been stored by Amazon Transcribe, open a case with AWS Support.


The following quotas cannot be changed:

Description Quota
Audio file length 4:00:00 (four) hours (14,400 seconds)
Audio stream duration 4:00:00 (four) hours (14,400 seconds)
Audio file size 2 GB
Audio file size (call analytics) 500 MB
Size of a custom vocabulary 50 KB
Length of a custom vocabulary phrase 256 characters
Size of a custom vocabulary filter 50 KB
Number of custom vocabulary filters 100
Number of channels for channel identification 2
Number of days job records are retained 90
Minimum audio file duration 500 milliseconds (ms)

You can request a quota increase for the following resources:

Resource Default
Number of concurrent batch transcription jobs 250
Number of concurrent batch transcription jobs (Call Analytics) 100
Job queue bandwidth ratio 0.9
Number of concurrent HTTP/2 requests 25
Number of concurrent WebSocket requests 25
Total number of vocabularies per AWS account 100
Number of pending vocabularies 10
Number of concurrently training custom language models 3
Total number of custom language models per AWS account 10
Number of categories per AWS account (Call Analytics) 200
Number of rules per category (Call Analytics) 20

The following operations limits can also be increased upon request:


For information about requesting a quota increase, see AWS service quotas in the AWS General Reference.