Resize an image

For plain pixel dimensions — make this 800 pixels wide, halve it, fit it in a 1200 × 1200 box — use Image Resizer. Aspect ratio stays locked unless you unlock it.

For a form that specifies both a size in pixels and a size in kilobytes, use Exact Size + Dimensions. It is the only tool here that takes both constraints at once, and it resolves them the way the form intends: dimensions win, because you typed them, and any shortfall against the byte target is reported honestly instead of being met by quietly shrinking the picture.

For a passport, visa or ID image given in millimetres, use Passport Photo Resizer. For the signature box that so often sits next to it, use Signature Resizer.

A digital image has no physical size of its own. It has a pixel grid, and a number stored in the file saying how many of those pixels make up an inch. That number is the DPI, and it is what turns 35 × 45 mm into 413 × 531 pixels at 300 DPI.

This matters because a portal that asks for “35 × 45 mm at 300 DPI” is asking for two things: the right pixel count,and the DPI value written into the file so a printer reproduces it at the right physical size. Resizing to 413 × 531 without setting the DPI produces a file that is numerically correct and prints at the wrong size. The passport tool writes both.

Shrinking discards pixels, and they do not come back: enlarging a small image afterwards invents detail rather than restoring it. Start from the largest original you have. If the goal is only a smaller file and not smaller dimensions, compressing is usually the better move — it leaves the picture the size it is.

Everything here runs inside your browser tab. Your image never leaves your device — the privacy policy shows you how to confirm that in DevTools.