How to resize images without stretching them

A photo has a shape: width divided by height. If you force a new width and a new height that do not share that shape, the picture stretches. Faces get wide, circles become ovals, and the file looks broken even when the export “succeeded.” The fix is to decide one side, or a percentage, and let the other side follow.

Image Resize starts in dimension mode with Keep aspect ratio turned on. When you add one image, it reads the real pixel size and fills the width and height boxes with those numbers, and it prints the original size so you can see you are not guessing. Change the width, and the height updates from the original ratio. Change the height, and the width follows. That is the mode to leave on unless you have a reason not to.

Percentage mode is the other safe path. The slider runs from 5 to 200 and starts at 50. Both sides scale by the same factor, so the ratio checkbox is disabled — there is nothing to forget. Fifty percent of a 2000 by 1000 image is 1000 by 500. Numbers are rounded to whole pixels. A side never goes below 1 pixel. One hundred percent is a same-size redraw, which can still re-encode the file if you also change format or quality, so it is not a byte-for-byte copy.

It does not crop. If you need a 1200 by 630 rectangle out of a 4000 by 3000 photo, turning the ratio off and typing 1200 and 630 will squash the photo into that rectangle. The tool will not cut the sides off. Crop in an editor that shows you the window, then resize the cropped file here if the cropped file is still the wrong size.

It does not add detail when you enlarge. The slider goes to 200 percent because sometimes a layout demands a larger pixel count. The canvas draws the same picture into more pixels with smoothing. Edges get soft. If you have a larger original, use that instead of scaling a thumbnail up. Enlarging is the wrong tool for “this old photo is small and I want it sharp.”

It does not read HEIC, GIF, or PDF. Export a JPG or PNG first. Each source must be 40 MB or smaller, and the result cannot exceed 16,384 pixels on a side. A huge poster scaled up can hit that stop even when the source opened.

One image uses the width and height boxes as the target when you are in dimension mode. Several images do not all share one height if Keep aspect ratio is on. The width you typed is applied to each file, and each file’s height is computed from its own shape. A set of phone photos can share a width without sharing a crop. The page says this under the controls when more than one file is listed.

If you turn the ratio off on a batch, every file is forced to that exact width and height. Mixed portraits and landscapes will stretch. That is useful only when every file is already the same shape and you are hitting a required pixel size.

Percentage mode on a batch scales each file from itself. A 50 percent batch of mixed sizes stays proportional and does not snap them all to one width. Use percentage when you want “half as big.” Use a shared width when you want “about this many pixels across.”

More than one output file downloads as resized-images.zip. One file downloads under its own name with the new extension. The zip is built in the browser.

You can keep the original format or save as JPG, PNG, or WebP. Quality starts at 90 and affects JPG and WebP. PNG disables the slider. JPG paints transparency white. If all you needed was a different format and the size is already right, Image Convert avoids a resize you do not need. If all you needed was a smaller file for email and you do not care about an exact pixel count, Image Compress caps the long edge at 1920 by default and shows the before and after sizes.

Doing both a big shrink and a low JPEG quality is two losses. For a delivery file, shrink the dimensions first and leave quality high, then lower quality only if the file is still too large. Work from the original each time. A stretched or blocky download is a bad source for a second attempt.

Drop the file and wait until the original size is printed. Leave the ratio on. Type the width you need. Confirm the height that appears is the shape you expect — a 4:3 photo should not become square. Pick the format. Download. Open it. If it is soft, you either enlarged it or saved a JPG too aggressively. If it is stretched, the ratio was off. Delete that download and run the original again. The tool never overwrites the file you dropped; the browser saves a new one.

The decode and the draw stay on the device. QuickConvert does not receive the image. The notes on what the website around the tool may still do are in privacy with online file tools. Format tradeoffs are in JPG vs PNG vs WebP.