How to resize an image
- Tap Choose a photo and pick the image you want to resize.
- It starts at half size. Pick another named size, or type a width and let the height follow.
- Switch the unit to cm, mm or inches if a form asked for a physical size.
- Tap Resize photo, then save the result.
Pixels, percentages and centimetres are three different questions
A website or a social profile wants pixels: a fixed grid, and anything else is the wrong answer. A photograph you are trimming for email wants a percentage, because half of whatever you started with is usually close enough. A printed form wants centimetres, and that is the one that trips people up, because centimetres are not a size a file has until you also say how many dots go in each inch.
This page handles all three, and when you choose a physical unit it shows the arithmetic: 3.5 by 4.5 centimetres at 300 DPI is 413 by 531 pixels. If a form gave you both a physical size and a pixel size and they disagree, that line is how you find out which DPI they had in mind.
Leave one side blank and the shape takes care of itself
Type a width and leave the height empty, and the height is worked out from your photo’s own proportions. That is almost always what you want: forcing both numbers on an image whose shape does not match will squash somebody’s face, and no amount of resizing fixes that afterwards.
When you genuinely need both numbers — a square profile picture, a fixed print size — unlock the shape with the button between the two fields and type both. The tool will do exactly what you asked and will not argue about it.
Making an image bigger is not the same as recovering detail
Enlarging is switched off by default. A 300-pixel photo asked to become 1200 pixels does not gain three quarters of its detail back — it invents it, and it looks soft. If a form insists on a size larger than your file, the honest fix is a better source image, and the second-best fix is to enlarge and accept the softness knowingly rather than by accident.