A square 400 x 400 image - a square profile picture. Upload your picture below and download it at exactly this size.
Tip: start from the largest original you have - enlarging a small picture to 400 x 400 will look soft.
Choose your picture, check that width is 400 and height is 400, pick how it should fit (crop, fit inside, or stretch), and click Resize. Then download the result.
It is commonly used for a square profile picture. Platforms change their guidelines from time to time, so check the current recommended size if an upload looks wrong.
Not unless you choose Stretch. "Fill & crop" scales the picture to cover the 400 x 400 area and trims the overflow; "Fit inside" keeps the whole picture and adds a background colour.
No. Everything runs in your browser, so your photo stays on your device.
After resizing, run the file through the compress tool to bring it under a size limit such as 50 KB or 200 KB.