Resize Image
Set an exact pixel width and height with an aspect lock, using stepped downscaling that keeps small versions sharp.
Resize Image workspace
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Select or drop an image file
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Using Resize Image
Choose an image. Its real pixel dimensions load into the width and height boxes.
Type a new width or height, or pick one of the six presets such as the Open Graph or avatar size.
Leave Lock aspect ratio ticked to keep the proportions, or untick it to set both numbers independently.
Pick an output format if you do not want to keep the source format, then process and download.
Reductions run as repeated halving passes on an offscreen canvas before the final draw, which is why small versions keep their detail instead of aliasing. The output format follows the source file unless you change it, so transparency survives by default.
Resizing Images Without the Staircase Edges
Shrinking a 4,000 px photo to 400 px in a single draw looks crunchy, and it's nothing to do with your file. The browser samples only a handful of source pixels for each destination pixel and throws the rest away, so fine detail collapses into jagged steps. This tool reduces in stages to avoid that, and the other controls are simpler than they look.
Halving, then halving again
Each reduction runs as a chain of halving passes on an offscreen canvas, with smoothing set to its highest quality, until the picture is within a factor of two of the size you asked for. Only the final draw lands on your exact numbers. Every pass averages four pixels into one, so by the end almost every source pixel has fed into the result. Text in a screenshot stays legible at quarter size, and hair, fence wire and fabric weave stop breaking up into speckle.
Width, height and the lock
While the aspect lock is on, type a width and the height follows, or the other way round. Switch the lock off and the two boxes move independently, which stretches the picture. That's occasionally what a banner needs, but usually it isn't.
Six presets cover the common targets: Instagram square and story, a YouTube thumbnail, an Open Graph card, HD, and a 512 px avatar. How they behave depends on that same checkbox. With the lock on, a preset is treated as a box to fit inside, so a landscape photo sent to 1080 x 1080 comes back 1080 x 720 instead of being squashed into a square. With the lock off, the preset sets both numbers exactly. If you really do need to fill a square frame, cut the picture to shape first in Crop Image, then scale it here.
The saved file is a fresh encode
Unless you change the output format, you get back what you started with: a JPEG returns as a JPEG and a PNG keeps its alpha channel. Saving re-encodes the pixels, though, so a JPEG loses a little more every time it passes through. If you work from the camera original and not yesterday's export, the loss happens once instead of five times.
Picking JPEG or BMP for a source with transparency will ask you for a background colour first. Neither container has an alpha channel, and untreated transparency would come out black.
Going bigger buys you nothing
Enlarging an image only interpolates between the pixels you already have. Doubling a 300 px thumbnail gives you a 600 px image with the same information spread more thinly and slightly softer edges. No browser can invent detail the original never recorded, so use upscaling to meet a minimum-size requirement and don't expect it to repair anything.
Two things this tool doesn't offer
There's no percentage input and no bicubic-versus-bilinear menu. Earlier copy on this page described both, but neither existed. What you get is the browser's high-quality resampling path, applied repeatedly.
There's also no DPI field in the output. Canvas can't write a resolution tag into the file it hands back, so the DPI selector is really a print-size calculator: choose 300 and it tells you how many inches wide the image will print. If you're aiming at a file size instead of a pixel dimension, Compress Image is the page that measures the result and tells you the percentage saved.
Frequently asked
Why do my downscaled photos look sharper here than elsewhere?
Large reductions are performed as a chain of halving passes rather than one jump. Each pass averages four pixels into one, so nearly every source pixel contributes to the result instead of being skipped by the sampler.
Where is the percentage box and the interpolation quality menu?
Neither was ever built, although older documentation described both. You set a width and a height in pixels, and the resampling always uses the browser's highest-quality smoothing path.
Why did a 1080 x 1080 preset give me a 1080 x 720 image?
With the aspect lock on, a preset is treated as a box to fit inside rather than a shape to stretch to. Turn the lock off if you want the exact preset dimensions and accept the distortion.
Can I set the DPI of the resized file?
No. A canvas export cannot write a resolution tag into an image file, so the DPI selector is a print-size calculator: it tells you how many inches wide the picture will print at 72, 150 or 300 DPI.