Width 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 thecompatibility 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 insecure contexts (HTTPS), in some or allsupporting 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.

Warning:TheWidth header was standardized asSec-CH-Width and the new name is now preferred.

The HTTPWidthrequest header is adevice client hint which indicates the desired resource width in physical pixels — the intrinsic size of an image. The provided pixel value is a number rounded to the smallest following integer (i.e., ceiling value).

The hint is only sent on image requests.

The hint allows the client to request a resource that is optimal for both the screen and the layout: taking into account both the density-corrected width of the screen and the image's extrinsic size within the layout.

If the desired resource width is not known at the time of the request or the resource does not have a display width, theWidth header field can be omitted.If theWidth header appears more than once in a message the last occurrence is used.