index.md

---

title: Content-DPR
slug: Web/HTTP/Headers/Content-DPR
status:
  - deprecated
  - non-standard
browser-compat: http.headers.Content-DPR

---

{{HTTPSidebar}}{{deprecated_header}}{{securecontext_header}}{{Non-standard_header}}

The Content-DPR response header is used to confirm the image device to pixel ratio in requests where the screen {{HTTPHeader("DPR")}} client hint was used to select an image resource.

Header type	{{Glossary("Response header")}}, Client hint
{{Glossary("Forbidden header name")}}	no
{{Glossary("CORS-safelisted response header")}}	no

If the {{HTTPHeader("DPR")}} client hint is used to select an image the server must specify Content-DPR in the response. If the value in Content-DPR is different from the {{HTTPHeader("DPR")}} value in the request (i.e. image DPR is not the same as screen DPR) then the client must use the Content-DPR for determining intrinsic image size and scaling the image.

If the Content-DPR header appears more than once in a message the last occurrence is used.

Note:

• Content-DPR was removed from the client hints specification in draft-ietf-httpbis-client-hints-07. The Responsive Image Client Hints spec proposes to replace this header by specifying intrinsic resolution/dimensions in EXIF metadata.

Syntax

Content-DPR: <number>

Directives

• <number>

  • : The image device pixel ratio, calculated according to the following formula: Content-DPR = Selected image resource size / (Width / DPR)

Examples

See the DPR header example.

Browser compatibility

{{Compat}}

See also

• Improving user privacy and developer experience with User-Agent Client Hints (web.dev)

• Device client hints

  • {{HTTPHeader("Device-Memory")}}

  • {{HTTPHeader("DPR")}}

  • {{HTTPHeader("Viewport-Width")}}

  • {{HTTPHeader("Width")}}

• {{HTTPHeader("Accept-CH")}}

• HTTP Caching > Varying responses and {{HTTPHeader("Vary")}}