Amazon Comprehend
Developer Guide

Guidelines and Limits

Important Notice

Amazon Comprehend Medical is not a substitute for professional medical advice, diagnosis, or treatment. Amazon Comprehend Medical provides confidence scores that indicate the level of confidence in the accuracy of the detected entities. Identify the right confidence threshold for your use case, and use high confidence thresholds in situations that require high accuracy. For certain use cases, results should be reviewed and verified by appropriately trained human reviewers. Amazon Comprehend Medical should only be used in patient care scenarios after review for accuracy and sound medical judgement by trained medical professionals.

Keep in mind the following information when using Amazon Comprehend Medical.

Supported Regions

For a list of AWS Regions where Amazon Comprehend Medical is available, see AWS Regions and Endpoints in the Amazon Web Services General Reference.


For information about throttling and limits for Amazon Comprehend Medical, see url=""

Overall Limits

All Amazon Comprehend Medical operations have the following limits:

Description Limit
Character encoding UTF-8
Maximum document size (UTF-8 characters) for DetectEntity and DetectPHI operations. 20,000 bytes
Maximum size of batch jobs (all files) 10 Gb
Minimum size of batch jobs (all files) 1 byte
Maximum individual file size for batch jobs 40 Kb
Maximum number of files for batch jobs 5 million

Amazon Comprehend Medical processes one block of each text document at a time, synchronously. Only documents in English (EN) are supported.