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Service limits for Azure AI Translator Service

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This article provides both a quick reference and detailed description of Azure AI Translator Service character and array limits for text and document translation.

Text translation

Charges are incurred based on character count, not request frequency. Character limits are subscription-based.

Character and array limits per request

Each translate request is limited to 50,000 characters, across all the target languages. For example, sending a translate request of 3,000 characters to translate to three different languages results in a request size of 3,000 × 3 = 9,000 characters and meets the request limit. You're charged per character, not by the number of requests, therefore, we recommend that you send shorter requests.

The following table lists array element and character limits for each text translation operation.

Operation Maximum Size of Array Element Maximum Number of Array Elements Maximum Request Size (characters)
Translate 50,000 1,000 50,000
Transliterate 5,000 10 5,000
Detect 50,000 100 50,000
BreakSentence 50,000 100 50,000
Dictionary Lookup 100 10 1,000
Dictionary Examples 100 for text and 100 for translation (200 total) 10 2,000

Character limits per hour

Your character limit per hour is based on your Translator subscription tier.

The hourly quota should be consumed evenly throughout the hour. For example, at the F0 tier limit of 2 million characters per hour, characters should be consumed no faster than roughly 33,300 characters per minute. The sliding window range is 2 million characters divided by 60 minutes.

You're likely to receive an out-of-quota response under the following circumstances:

  • You reached or surpassed the quota limit.
  • You sent a large portion of the quota in too short a period of time.

There are no limits on concurrent requests.

Tier Character limit
F0 2 million characters per hour
S1 40 million characters per hour
S2 / C2 40 million characters per hour
S3 / C3 120 million characters per hour
S4 / C4 200 million characters per hour

Limits for multi-service subscriptions are the same as the S1 tier.

These limits are restricted to Microsoft's standard translation models. Custom translation models that use Custom Translator are limited to 3,600 characters per second, per model.

Latency

The Translator has a maximum latency of 15 seconds using standard models and 120 seconds when using custom models. Typically, responses for text within 100 characters are returned in 150 milliseconds to 300 milliseconds. The custom translator models have similar latency characteristics on sustained request rate and can have a higher latency when your request rate is intermittent. Response times vary based on the size of the request and language pair. If you don't receive a translation or an error response within that time frame, check your code, your network connection, and retry.

Document Translation

Note

  • Document Translation doesn't support translating secured documents such as those with an encrypted password or with restricted access to copy content.
  • When translating documents with content in multiple languages (batch operations only), the feature is intended for complete sentences in a single language. If sentences are composed of more than one language, the content may not all translate into the target language.
Asynchronous (batch) operation limits
Attribute Limit
Document size ≤ 40 MB
Total number of files. ≤ 1000
Total content size in a batch ≤ 250 MB
Number of target languages in a batch ≤ 10
Size of Translation memory file ≤ 10 MB
Synchronous operation limits
Attribute Limit
Document size ≤ 10 MB
Total number of files. 1
Total number of target languages 1
Size of Translation memory file ≤ 1 MB
Translated character limit 6 million characters per minute (cpm).

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