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  1. HTTP (Hypertext Transfer Protocol)
  1. HTTP Headers
  1. Content-Length
    1. Writing messages
    2. Reading messages
    3. Overview table
    4. Syntax
      1. Example

Content-Length

The Content-Length header specifies the length (in bytes) of the message body.

Writing messages

Set this header to the number of bytes that the message body occupies, which is sent immediately after the final ␍␊␍␊. If the exact length is not yet known, the server can omit this header, but must use Connection: close (if HTTP/1.0) or chunked encoding (if HTTP/1.1).

Reading messages

Implementations should ensure the provided number does not overflow the internal integer representation. This header is not the only way the message length may be calculated, see RFC 7230 §3.3.3. Message Body Length for how to determine the message body length.

Overview table

Name
Content-Length
Description
Specifies the size (bytes) of the attached message body.
Direction
Both
Specification
RFC 7230: HTTP/1.1 Message Syntax and Routing §3.3.2. Content-Length

Syntax

Content-Length = 1*DIGIT

Example

Content-Length: 3495