How resizing works
Each image is opened in your browser, turned the right way up using the rotation your camera stored in it, and drawn onto a canvas of the new size with the browser's high-quality smoothing. The canvas is then saved as a new file. Nothing is sent anywhere, so a batch of 50 photos takes as long as your device needs and no longer.
Keep proportions, width given: new height = width × original height ÷ original width (rounded to whole pixels)
Percentage: new width = original width × % ÷ 100, same for height
Worked example
A phone photo is 4032 × 3024 pixels and 3.1 MB, and a listing site wants images 1600 pixels wide. Type 1600 in Width, leave Height empty and keep proportions on. The new height is 1600 × 3024 ÷ 4032 = 1200, so the photo becomes 1600 × 1200. That is 1.9 megapixels instead of 12.2, about a sixth of the pixels, and the JPG typically drops to a few hundred KB. Drop 30 photos at once and all of them get the same treatment; portrait photos (3024 × 4032) come out 1600 × 2133.
Common sizes
| Use | Size | How the tool fits it |
|---|---|---|
| Instagram square post | 1080 × 1080 | Fills exactly, trims the sides or top and bottom |
| Instagram portrait post | 1080 × 1350 (4:5) | Fills exactly |
| Instagram story or reel | 1080 × 1920 (9:16) | Fills exactly |
| US passport digital photo | 600 × 600 | Fills exactly; frame the head with the passport photo maker first |
| Full HD screen | Fits in 1920 × 1080 | Shrinks to fit, never enlarges or crops |
| 4K screen | Fits in 3840 × 2160 | Shrinks to fit |
| Email attachment | Longest side 1600 | Shrinks to fit |
Privacy and what changes
Your images never leave your device. The resized files are new images, so they do not carry the original EXIF details such as GPS location, date taken or camera model. Animated GIFs come out as a still JPG of the first frame. If you need a file under a certain size rather than a certain pixel count, resize first and then run the result through the compress tool.
Questions people ask
How do I resize a photo without stretching it?
Leave "Keep proportions" on and fill in only the width or only the height; the other side is worked out for you. If you fill in both, the photo is scaled to fit inside that box, so one side may come out smaller than you typed. Turn "Keep proportions" off only when you really want the exact width and height, which squashes or stretches the picture.
What happens with the Instagram presets if my photo is a different shape?
The square, portrait (4:5) and story (9:16) presets fill the exact size by trimming the overflow equally from both sides, the same way Instagram crops. A wide landscape photo set to 1080 × 1080 loses its left and right edges. If you want to choose what gets trimmed, use the crop tool first and then resize.
Can I make a small image bigger?
Yes, in pixel mode or up to 400% in percentage mode, but enlarging cannot add detail that was never captured. The result will look softer, and the list marks those files as enlarged. The Full HD, 4K and email presets never enlarge: a photo already smaller than the preset keeps its size.
Does resizing reduce the file size?
Usually by a lot, because file size roughly follows the number of pixels. Halving the width and height leaves a quarter of the pixels. The list shows each new file size. For an exact size limit such as "under 200 KB", use the compress tool, which can also lower JPG quality.
Which format will my resized files be saved in?
By default each file keeps its format: JPG stays JPG, PNG stays PNG and WebP stays WebP (except in Safari, which cannot save WebP, so those become JPG). GIF, BMP and AVIF are saved as JPG because browsers cannot write them. JPG and WebP are saved at quality 92, which looks the same as the original on screen. Transparent areas turn white in JPG.
Is there a limit on how many images I can resize?
Up to 200 files at a time, or about 1.5 GB in total on a computer (400 MB on a phone), so your browser does not run out of memory. Outputs are limited to 16,384 pixels on a side and 16.7 megapixels in total, the largest size phones can draw.