How to resize a photo for online forms: pixels, KB and cm explained
Application forms often ask for a photo or signature in three different units at once: dimensions, file size and format. Getting all three right on the first try is easy once you know how they relate and which order to work in.
The three numbers a form can ask for
- Dimensions in pixels, for example 200 × 230.
- File size in KB or MB, for example under 50 KB.
- File type, usually JPG, sometimes PNG.
If the form gives centimetres or inches
Screens use pixels, so a size in centimetres needs converting. Pixels equal inches multiplied by the resolution in DPI, and 1 inch is 2.54 cm. At 300 DPI, a photo of 3.5 × 4.5 cm works out to about 413 × 531 pixels.
If the form does not state a resolution, 300 DPI is a safe choice for photos that may be printed.
The order that works best
- Crop the photo to the right shape first, so the face or signature fills the frame.
- Resize it to the exact pixel dimensions.
- Compress it to the file-size limit, keeping it a JPG.
- Check the result: dimensions, size and that it still looks clear.
Fill, white margins or stretch?
When your picture has a different shape from the target, you have three choices. Filling the size and cropping the edges keeps everything looking natural and suits face photos. Fitting with white margins keeps every part of the picture and suits signatures. Stretching to fit distorts the picture, so it is best avoided.
Tips for clearer photos and signatures
- Use daylight and a plain background for photos.
- Sign with a dark pen on plain white paper, and photograph it flat without shadows.
- Keep the original file. If a form rejects the result you can start again from it.