Three ways to set the size
- Longest side — the simplest. Say 1,600 pixels and a landscape photo becomes 1,600 wide, a portrait one 1,600 tall; the other side follows so nothing is stretched. Use it when you have a batch of mixed photos or a rule like “no more than 2,000 px”.
- Width × height — for an exact size a form or template asks for. With Keep aspect ratio on, typing one side fills in the other.
- Percentage — half, a quarter, or any share of the original.
When the shape doesn't match
Turn off Keep aspect ratio and type a width and height of a different shape — a square from a 4:3 photo, say — and you choose what happens to the difference:
- Fill and crop the edges: the photo covers the whole box and the overflow is trimmed evenly from both sides. Best for avatars and thumbnails.
- Fit inside: the whole photo is kept and fits within the box, so one side comes out shorter than you typed.
- Fit and pad: the whole photo, centred on a canvas of exactly your size; the bars are transparent in PNG and WebP, and white in a JPEG.
- Stretch: exactly your size, distorting the photo. Rarely what you want, but there when a system insists.
Pixels and file size are different things
Resizing changes how many pixels a photo has. The file size follows, but not exactly: halving the width and height leaves a quarter of the pixels, and the file usually shrinks by somewhat less than that, because each remaining pixel carries more detail. If what you really have is a limit in KB, use compress to KB instead — it picks the dimensions and quality for you and tells you the exact result.
Quality and format
Resizing uses a Lanczos filter, which keeps edges sharp when making a photo smaller, and works in premultiplied alpha so transparent edges don't pick up a dark fringe. Same format keeps a JPEG a JPEG, a PNG a PNG and a WebP a WebP; other inputs become JPEG, or PNG if they have transparency. For JPEG you set the quality (85 is a good default — above about 92 the file grows quickly with little visible gain). PNG and WebP here are lossless.
You can make an image larger, too, but enlarging only adds pixels, not detail: a 600-pixel photo blown up to 2,400 will look soft. The page tells you when the result is bigger than the original.
Printing
For a print, the pixels you need are the print size times the printer's resolution. At the usual 300 pixels per inch, a 4 × 6 inch print needs 1,200 × 1,800 pixels, and a 10 × 15 cm print about 1,181 × 1,772. Type those as width and height. This page doesn't write a DPI value into the file; most printing services work from the pixels and the print size you order.
What else changes
The photo is turned upright using its orientation tag, and the new file carries no EXIF data — no location, no camera details. A colour profile is kept. To remove metadata without touching the pixels at all, use the EXIF remover.