Resize a JPG

1. Set the size you want. Type a width and a height in pixels, switch to Percent, or pick a platform size. With Keep the aspect ratio ticked, one number fills in the other.
2. Choose the JPG on your device. Drag it onto the panel above or press Choose an image, up to 20 MB. It is read where it already sits, so there is no transfer to wait through.
3. Press Resize image. Your device decodes the JPEG, resamples it to the new dimensions and writes a fresh JPEG. The output format stays on Original, so a JPG in is a JPG out.
4. Download the new JPG. The panel prints the size before and after and the dimensions actually produced, so you can check the result before you keep it.

A JPEG cannot be resized in place. The file has to be decoded back to raw pixels, resampled to the new dimensions, and compressed again — and that last step is a fresh generation of lossy compression, written here at quality 80.

In practice this matters less than it sounds, because you are usually shrinking. What it does mean is that repeated round trips add up: resizing the same photo four times to four different widths from the same original is fine, while resizing yesterday’s output again today is not the same thing. Keep the original and always work from it.

Downscaling averages several source pixels into each output pixel, and that averaging happens to smooth over the blocking and the halo-like ringing an earlier JPEG save left behind. A slightly rough photograph often looks cleaner at half its size than it did at full size.

Enlarging does the reverse. There is no extra detail to draw on, so the resampler spreads what is there across more pixels — and it spreads the artefacts too, turning a subtle 8-pixel pattern into a visible 30-pixel one. Stay at or below the original dimensions whenever you can.

JPEG compresses in 8×8 pixel blocks, and it stores colour at half the resolution of brightness in each direction — that is the standard 4:2:0 arrangement our output uses. On a 2000-pixel photo neither fact is noticeable. On a 120-pixel avatar, each block is a much larger share of the image, and coarse colour starts to show on anything saturated.

So for small interface graphics — avatars with lettering, badges, icons, anything with thin type or hard edges at 200 pixels or less — switch the output format to PNG in the settings above, or start from a PNG. For small photographs, JPEG is still fine.

The format select above sits on Original, so a JPG goes in and a JPG comes out with the same extension and a recognisable filename. You can override it in the same pass: choosing WebP typically takes another quarter to a third off the file, and choosing PNG will make a photograph substantially heavier because PNG has no way to compress photographic detail.

Resizing a PNG instead works differently and has its own page. If your photo has to come in under a specific byte limit, resize it here first and then compress it to a target size — dimensions are the blunt lever and quality is the fine one.

20 MB per file and 8000 pixels on the longest side, in or out. JPEG, PNG and WebP are accepted, and the same three come back.

The resizing is done by your own device. The JPG is opened where it already is and the smaller one is written on the same machine, so nothing is transmitted and there is no copy of your photo anywhere else. The output is built from raw pixels, which is why it carries no EXIF or GPS data. If a photograph is too large for the memory your browser can spare, the panel says so before it starts.