Resize image

A tool that changes how many pixels an image has, by resampling it to a new width and height. This one takes any number of files at once, sizes each by pixels, its longest side, a percentage or a print size at a chosen ppi, can hold each file under a byte limit, and writes the resolution into the file it hands back.

• Upright, in the colours the camera saw

  A phone stores a portrait photo sideways with a tag that says “turn me”, usually in Display P3 rather than sRGB. Each file is turned by its tag, checked against its header, and converted to sRGB, and the page says per file what was done.

  Measured 8 October 2026 on a portrait phone photo stored sideways in Display P3, asked for 1080 wide: imageresizer.com dropped the colour profile (a red of 220, 30, 30 came out 202, 54, 44), iLoveIMG made it 810 wide, and simpleimageresizer.com squashed it to 4:3.

• A print size the file remembers

  Type 15 × 10 cm at 300 ppi and the arithmetic is printed under the boxes. The ppi is then written into the JPEG or PNG, so a layout or print app places the photo at 15 cm instead of guessing from 72.

  15 ÷ 2.54 × 300 = 1771.65, so 1772 px. None of the five online resizers measured writes a resolution: every file came back saying 72 with no unit.

• Under a file size, or it says so

  Set “Under” in KB and each file lands at or below it: quality comes down first, in a binary search, and the pixel size only shrinks when quality alone cannot get there. A file that cannot be made small enough is flagged, never passed off.

  Held at or under 20, 50, 100 and 200 KB by tests with the same MozJPEG encoder the page runs. 1 KB is counted as 1,000 bytes, so a result also clears a form that counts 1,024.

• Lanczos3, not the browser’s scaler

  Resampling runs pica’s Lanczos3 in a worker, one image at a time, so a batch of forty never freezes the page or the phone. Optional light or strong sharpening runs after the resize.

  Against a Lanczos3 reference on a zone-plate test image: Chromium’s canvas scaler scored 21.33 dB by default and 27.03 dB at its “high” setting, Safari’s engine 21.37 dB either way, and this page’s Lanczos3 pass 37.33 dB.

1. 1

   Add the photos

   Choose or drop as many as you need. Each one’s size is read from its header, the right way up, before anything is decoded.

2. 2

   Say how big

   Pixels for an exact width or height, Longest side for a mixed batch of portrait and landscape shots, Percent, or Print size in cm, mm or inches at a ppi.

3. 3

   Choose what comes out

   Under More options, whose summary line says what is set: JPEG, PNG, WebP where the browser can write it, or the same type as each file; a quality, or a size in KB to stay under; the ppi to write in; sharpening.

4. 4

   Resize and download

   The Resize button turns into Download once every file is done: one file saves on its own, several come as one .zip, and Download stays on the bar at the foot of the screen. Every card shows the size reached in pixels and bytes.

• How to resize a photo to an exact size: pixels, print size or file sizeResize photos to an exact width, a long side, a print size at 300 ppi or under a KB limit, and keep them upright, in true colour and without GPS.

• HEIC opens only where the browser decodes it (Safari). Elsewhere it needs exporting as JPEG first; the decoder library for it is LGPL, which this site does not ship.
• Output is capped at 8,192 pixels a side and 16,777,216 pixels in total, the browser canvas ceilings past which a canvas returns a blank image.
• WebP output needs a browser that can write WebP; Safari cannot, so the option is not offered there and the page says why, rather than quietly saving a PNG.