Device-Memory header

{{SecureContext_Header}}{{Non-standard_Header}}

[!WARNING] The Device-Memory header was standardized as {{HTTPHeader("Sec-CH-Device-Memory")}} and the new name is now preferred.

The HTTP Device-Memory {{Glossary("request header")}} is used in device client hints to indicate the approximate amount of available RAM on the client device, in gigabytes. The header is part of the {{DOMxRef("Device Memory API", "Device Memory API", "", "nocode")}}.

Client hints are accessible only on secure origins. A server has to opt in to receive the Device-Memory header from the client, by first sending the {{HTTPHeader("Accept-CH")}} response header. Servers that opt in to the Device-Memory client hint will typically also specify it in the {{HTTPHeader("Vary")}} header to inform caches that the server may send different responses based on the header value in a request.

Syntax

Device-Memory: <number>

Directives

• <number>

  • : The approximate amount of device RAM.

    The amount of device RAM can be used as a {{glossary("fingerprinting")}} variable, so values for the header are intentionally coarse to reduce the potential for its misuse. Values are only reported in powers of two, and are clamped to an implementation-defined minimum lower value and a maximum upper value. These bounds may change over time (see browser compatibility table).

    For example, if a browser does not report below 2 or above 32 then the value is one of: 2, 4, 8, 16, 32.

Examples

The server first needs to opt in to receive Device-Memory header by sending the {{HTTPHeader("Accept-CH")}} response header containing Device-Memory:

Accept-CH: Device-Memory

Then on subsequent requests the client might send Device-Memory header back:

Device-Memory: 1

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Improving user privacy and developer experience with User-Agent Client Hints (developer.chrome.com)
• {{DOMxRef("Device Memory API", "Device Memory API", "", "nocode")}}
• {{DOMxRef("Navigator.deviceMemory")}}
• {{DOMxRef("WorkerNavigator.deviceMemory")}}
• Device and responsive image client hints
  • {{HTTPHeader("Sec-CH-Device-Memory")}}
  • {{HTTPHeader("Sec-CH-DPR")}}
  • {{HTTPHeader("Sec-CH-Viewport-Height")}}
  • {{HTTPHeader("Sec-CH-Viewport-Width")}}
  • {{HTTPHeader("Sec-CH-Width")}}
  • {{HTTPHeader("DPR")}} {{deprecated_inline}}
  • {{HTTPHeader("Content-DPR")}} {{deprecated_inline}}
  • {{HTTPHeader("Viewport-Width")}} {{deprecated_inline}}
  • {{HTTPHeader("Width")}} {{deprecated_inline}}
• {{HTTPHeader("Accept-CH")}}
• HTTP Caching: Vary and {{HTTPHeader("Vary")}}