Facebook cover photo size
Mobile shows a narrower slice than desktop, keep content centred.
Cropped in your browser · your image is never uploaded
Facebook displays a cover at 851 × 315 on desktop and 640 × 360 on mobile — different aspect ratios, so the same file cannot fill both. Upload at 1702 × 630 for sharpness on high-density screens.
How to use the facebook cover photo size
The two display sizes are the whole problem: desktop is wider and shorter, mobile is narrower and taller, and Facebook crops the same upload differently for each. What survives both is a centred region roughly 640 wide within the 851, so text near the left or right edge is visible on a laptop and gone on a phone, where most of your audience is. On a personal profile the profile picture also punches into the lower left of the cover, which removes another corner. Upload at double resolution: Facebook re-compresses regardless, and giving it more pixels to start from produces a visibly cleaner result.
Questions
851 × 315 on desktop and 640 × 360 on mobile. Upload at 1702 × 630 for a sharp result on high-density screens.
Because mobile uses a different aspect ratio than desktop. Only the centred region survives both.
On a personal profile, yes; it overlaps the lower left corner. Pages place it differently.
JPEG for photographs. Facebook suggests PNG for images with a logo or text, since its compression is kinder to flat colour.
Facebook re-compresses every upload. Uploading at double size gives its encoder more to work with.