Count tokens in a Message

Count the number of tokens in a Message.

The Token Count API can be used to count the number of tokens in a Message, including tools, images, and documents, without creating it.

Learn more about token counting in our user guide

post/v1/messages/count_tokens

Headers

anthropic-versionstring

The version of the Claude API you want to use.

Read more about versioning and our version history here.

The version of the Claude API you want to use.

Read more about versioning and our version history here.

anthropic-user-profile-idstring

The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization. Requires the user-profiles beta header.

Request body

Example request

{
  "messages": [
    {
      "content": "Hello, world",
      "role": "user"
    }
  ],
  "model": "claude-opus-5"
}

Response

Successful Response

input_tokensinteger required

The total number of tokens across the provided list of messages, system prompt, and tools.

Example response

{
  "input_tokens": 2095
}

Changes

Changed in 22 of the 68 revisions of this API.123142

Sep 1, 2026d1d189d791d121See the full diff
- ●
  removed the request property ///
  request-property-removed
- ●
  removed the request property ///
  request-property-removed
- ○
  added subschema #2 subschema #3 to the request property anyOf list
  request-property-any-of-added
This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog
Aug 19, 202667ee007cda1c26See the full diff
- ○
  added the new optional request property ///////////////
  new-optional-request-property
- ○
  added the new optional request property //////
  new-optional-request-property
- ○
  added the new optional request property ////////////
  new-optional-request-property
- ○
  added the new optional request property //////
  new-optional-request-property
- ○
  added the new optional request property //////////
  new-optional-request-property
- ○
  added the new optional request property ////////////////
  new-optional-request-property
- ○
  added the new optional request property //////
  new-optional-request-property
- ○
  added browser_state discriminator mapping keys to the //////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the ///////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the /////////////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the ////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the ////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the //////////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the ////////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the ////////// request property
  request-property-discriminator-mapping-added
- ○
  added file discriminator mapping keys to the //////////////// request property
  request-property-discriminator-mapping-added
- ○
  added to the / request property oneOf list
  request-property-one-of-added
- ○
  added to the ///////// request property oneOf list
  request-property-one-of-added
- ○
  added to the ////// request property oneOf list
  request-property-one-of-added
- ○
  added to the ////////// request property oneOf list
  request-property-one-of-added
- ○
  added to the /////////////// request property oneOf list
  request-property-one-of-added
- ○
  added to the ////// request property oneOf list
  request-property-one-of-added
- ○
  added to the //////////// request property oneOf list
  request-property-one-of-added
- ○
  added to the ////////// request property oneOf list
  request-property-one-of-added
- ○
  added to the //////////////// request property oneOf list
  request-property-one-of-added
- ○
  added to the //////// request property oneOf list
  request-property-one-of-added
Aug 14, 2026e9d8152420c311See the full diff
- ▲
  removed from the //// request property oneOf list
  request-property-one-of-removed
- ○
  removed mid_conv_system discriminator mapping keys from the //// request property
  request-property-discriminator-mapping-deleted
This revision also has 2 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog
Aug 13, 20266e9020ec2b4127See the full diff
- ○
  the //////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the //////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the //////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the /////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the ///////////////////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the //////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the //////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
- ○
  the //////// request property's maxLength was increased from 255 to 500
  request-property-max-length-increased
Aug 6, 2026538e9bd0db771See the full diff
- ▲
  removed subschema #17 subschema #18 from the request property anyOf list
  request-property-any-of-removed
Jul 24, 2026a97790bd7f1811See the full diff
- ▲
  removed subschema #5 subschema #6 subschema #8 subschema #12 subschema #13 subschema #16 subschema #17 from the request property anyOf list
  request-property-any-of-removed
- ○
  added subschema #5 subschema #6 subschema #7 subschema #9 subschema #13 subschema #14 subschema #17 subschema #18 to the request property anyOf list
  request-property-any-of-added
Jun 30, 20267caa9a75ddbc1See the full diff
- ○
  added subschema #2 to the request property anyOf list
  request-property-any-of-added
Jun 29, 20264465f98f96c11See the full diff
- ○
  added to the / request property oneOf list
  request-property-one-of-added
Jun 25, 20269445a445fbbe1See the full diff
- ○
  added the new optional header request parameter anthropic-user-profile-id
  new-optional-request-parameter
Jun 18, 2026063bcb9d6cf9117See the full diff
- ▲
  removed subschema #17 subschema #18 subschema #19 subschema #20 subschema #21 from the request property anyOf list
  request-property-any-of-removed
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added the new code_execution_20260521 enum value to the request property ////
  request-property-enum-value-added
- ○
  added to the / request property oneOf list
  request-property-one-of-added
This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

Full history (22 revisions)