Image Resizer

How to resize an image

1. Drop an image onto the box or click to browse. The filename and current dimensions appear, and the width and height fields pre-fill with the original size.
2. Type a new width or height. With the aspect-ratio lock on (the default), the other dimension recalculates instantly.
3. Or type a percentage in the scale field instead: 50 halves both dimensions, 200 doubles them.
4. Click Resize and download. The output filename includes the new dimensions, like photo-1080x810.jpg, so you can tell versions apart at a glance.

A worked example: an Instagram-ready square source

Load a 4032 by 3024 phone photo. The status line reads the filename and "4032×3024". You want it 1080 pixels wide for Instagram, so type 1080 into the width field; with the lock on, height snaps to 810, preserving the 4:3 shape. Click Resize and download, and photo-1080x810.jpg lands in your downloads at a fraction of the original file size, since the pixel count dropped to about 7 percent of the original. If you had typed 25 into the percent field instead, you would get 1008 by 756, each dimension rounded to the nearest pixel. Typing in either pixel field clears the percent field, so the last thing you touched always wins.

How resizing preserves sharpness

The image is redrawn onto a canvas at the target size with the browser's high-quality smoothing enabled, which uses proper resampling rather than naive nearest-neighbor scaling; downscaled photos stay crisp instead of aliasing into jagged edges. JPEG input stays JPEG on output (encoded at 92 percent quality, a deliberately conservative setting that avoids visible artifacts), and everything else, including PNG with transparency, exports as PNG with transparency intact. The whole operation runs in your browser; your photo is never uploaded. One habit worth adopting: resize from the original every time rather than resizing a resize, because each generation of JPEG re-encoding costs a little quality, and originals cost nothing to keep.

Honest limitations

Upscaling is allowed up to 500 percent and works, but physics is not negotiable: enlarging invents pixels by interpolation, so a 200 percent enlargement is softer than a true high-resolution source. Use it for casual purposes, not print. The maximum output dimension is 12,000 pixels on either side, a guardrail for browser memory. There is no crop: unlocking the aspect ratio stretches the image to your exact numbers, which distorts it, so to change shape without distortion you need a crop tool first. Canvas re-encoding strips EXIF metadata, including orientation flags, so a photo whose rotation lived only in metadata may need rotating before resizing. And it is one image at a time, deliberately, with no batch queue.