A small avatar square, 400 by 400
The directory and profile mark
400 by 400 is a modest square for a staff directory, a speaker list, a comment avatar, or a profile photo field that rejects a huge upload. In the social presets, both the LinkedIn profile and the X profile are this size. It is not a feed post. An Instagram square is 1080 by 1080, and using this small file there means the app will enlarge it and the face will look soft. Keep a larger master, and export 400 by 400 as the delivery file the directory actually requested.
Compose for a circle
Many apps draw this square inside a circle. Corners disappear. Put the eyes in the center and leave hair and shoulders with a little room. Tiny type in the image will not be readable at avatar size, so skip captions inside the picture. Type 400 and 400, then preview the result small, the way a comment thread shows it, not only at 100 percent on a wide monitor. If the field asked for 300, that is a different page.
Type the pair on one portrait
Enter 400 in both fields. The resizer reads the first file you add and leaves extra selections alone. JPG, PNG, WebP, and GIF can be that file. The ceiling is 10000 pixels on a side, so a camera portrait becomes a shrink, which is the kind outcome. Enlarging a 80 pixel thumbnail up to 400 does not invent detail. Start from the original portrait. The resize stays on this device, which is the right place for a staff photo.
Small files and the kilobyte box
A 400 square JPEG is usually light already. If you still set a kilobyte target, it applies to JPEG and WebP. Leave the box blank and those formats save at quality 0.92. PNG ignores the kilobyte target, which suits a simple logo avatar. For a face, JPEG is the usual choice. If a form caps the upload at a very small weight, run the image compressor after the square is correct. Do not change 400 to some other number just to chase bytes.