The circle is the whole problem
Almost every platform stores a square profile picture and displays it as a circle. The corners are thrown away — about 21% of the image area — and people routinely compose a photo that looks right as a square and then loses the top of a head or the edge of a shoulder in the round.
So the preview shows the circle by default. What you see masked is what your followers will see. The file you download is still square, because that is what the upload expects; the mask is a viewing aid, not something baked into the output.
Why the exact pixel size matters less than it used to, and still matters
Platforms re-encode whatever you give them, so uploading something larger than the stated size is not fatal. But it is not free either: their re-encoding is tuned for throughput, not for your face, and starting from a file that is already the right dimensions avoids one extra generation of quality loss.
It also avoids the surprise of a platform cropping differently from how you expected. Handing it exactly what it asks for removes the guesswork.
Dimensions here were last checked in 2026-08, and the date is printed next to the picker. Platforms change these without announcement, so anything important is worth confirming against their current help page — a tool that quietly serves last year's numbers is worse than one that admits the risk.
Getting a good result from an ordinary photo
Fill the frame with your head and shoulders. A profile picture is displayed at 40 pixels across in most interfaces — smaller than a postage stamp — and a full-length photo becomes an unrecognisable smudge at that size. Crop close.
Aim slightly high. Faces sit better a little above centre in a circle, and the focal dot makes that a one-second adjustment rather than a re-crop.
Prefer PNG if the picture is a logo or has flat colour, JPG if it is a photograph. Either way the metadata is removed on the way out — worth knowing if the photo came off a phone with location recording switched on.