Content-DPR header
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.
The HTTP Content-DPR response header is used to confirm the image device to pixel ratio (DPR) in requests where the screen DPR client hint was used to select an image resource.
Note:
The Content-DPR header was removed from the client hints specification in draft-ietf-httpbis-client-hints-07.
The Responsive Image Client Hints specification proposes to replace this header by specifying intrinsic resolution/dimensions in EXIF metadata.
If the 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 DPR value in the request (i.e., image DPR is not the same as screen DPR), 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.
| Header type | Response header, Client hint |
|---|---|
| Forbidden request header | No |
| CORS-safelisted response header | No |
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
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Content-DPR request header
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- No support
- No support
- Non-standard. Check cross-browser support before using.
- Deprecated. Not for use in new websites.
See also
- Device and responsive image client hints
Accept-CH- HTTP Caching: Vary and
Vary - Improving user privacy and developer experience with User-Agent Client Hints on developer.chrome.com (2020)