Instagram Highlight Cover size: 1080 x 1920 pixels.

A highlight cover starts life as a Story frame, 1080 by 1920 pixels, whether you pick it from the highlight or upload it from the camera roll. Instagram takes a centred square out of that frame and masks it to a circle roughly 77 pixels across under your bio. Everything outside the square exists only to make the file a valid Story size.

So design inside a 600 pixel circle in the middle of the canvas, about 660 to 1260 pixels down and 240 to 840 across, which is what the safe zone below marks. A solid brand colour with one white line icon is the format that still reads at 77 pixels. Two or three words do not, and a screenshot of a photograph turns into grey mush at that size.

Two mistakes come up constantly. The first is uploading a square icon file: Instagram stretches it to fill 9:16 and then crops a circle out of the stretched result, so the icon comes back soft and slightly wrong. The second is placing the icon near the top, where a Story headline would go, which the centred crop removes entirely. Instagram publishes no pixel spec for highlight covers and the help page cited here could not be fetched, so these figures come from the 9:16 canvas and how the circle is cut from it.