The limits are 400x400 to 7680x4320 pixels, under 8MB, PNG or JPG. The more useful part is what LinkedIn does to your photo after you upload it.
crop.
5 articles tagged crop.
LinkedIn profile photo size, and what actually gets cropped
5 min What a professional headshot actually has to do
5 min A headshot has three jobs: be recognisably you, match the room you are walking into, and survive being shrunk to 48 pixels. Everything else is decoration.
Square, 4:5 or 3:4: which crop for which platform
4 min Most places show you a circle or a square. A few want a portrait rectangle. Shoot once with room around you and you can produce all of them from the same frame.
When the top of your head is cut off in a photo
5 min You cannot put back a skull that was never photographed. But you can frame around the cut so it reads as a deliberate crop instead of a mistake.
Why your photo crops differently on every platform
5 min You upload one square and get a circle here, a wide banner there, and your chin missing on the third. The fix is to build the photo for the worst crop rather than the best one.