Profile picture: the element seen most often on the platform, and the smallest of all

It is the circular image at the top of the profile. But the profile is where it appears least. In practice it is seen in comments, in the Stories bar, in the list of who liked, in messaging and in search results. In all of those it is small, sometimes only a few dozen pixels.

The upload is square and the crop is circular. Anything in the corners of the square disappears. People who upload a rectangular logo lose the ends and cannot work out why.

On size: always upload well above what appears on screen, as a square at a few hundred points of resolution, because the app generates the smaller versions from what you sent. Uploading small has no upside and limits every version.

• A tightly framed face. For a personal account, a face filling almost the whole circle beats any full body shot.
• A symbol, not a full logo. For a brand, the isolated symbol works; the version with the written name becomes a blur.
• High contrast against the background. The circle appears over both light and dark backgrounds, so the subject has to separate from both.
• One dominant colour. That is what lets the eye recognise the account before reading the name.

• Text. No text survives the size at which it is actually seen.
• Full body or landscape photos. They become an indistinct smudge.
• A horizontal logo. The circular crop eats the sides.
• A busy background. With no separation between subject and background there is no recognition.
• Changing it weekly. The picture exists to be recognised inside a list; changing it resets that learning.

The picture is the first profile element anyone processes, before the display name and long before the bio. And it is what makes the account get noticed when it shows up in a comment list among dozens of others.

There is also a trust effect: a profile with no picture or a generic one reads as abandoned or fake, and that drags down conversion for people who arrived through the content.

One test settles the argument: shrink the image to thumbnail size and look at it. If you cannot tell whose it is, someone who does not know you will not either.

• I recognise the account with the image shrunk to thumbnail size.
• There is no text that has to be read.
• The subject separates from both light and dark backgrounds.
• I uploaded a square, at a resolution well above what is displayed.
• I do not change the picture often.