---
title: Content-Length
summary: null
url: >-
  https://www.fastly.com/documentation/reference/http/http-headers/Content-Length
---

When a message does not have a Transfer-Encoding header field, a `Content-Length` header field can provide the anticipated size, as a decimal number of octets, for a potential payload body. For messages that do include a payload body, the `Content-Length` field-value provides the framing information necessary for determining where the body (and message) ends. For messages that do not include a payload body, the `Content-Length` indicates the size of the selected representation ([Section 3 of RFC7231](https://httpwg.org/specs/rfc7231.html#rfc.section.3)).