maratoolHow to resize an image to an exact pixel size
Type the width you need and the height follows. It all happens on a canvas inside your own browser.
A print shop wants exactly 2480 by 3508. An upload form refuses anything over 800 by 800. Any image editor can do this, but waiting for Photoshop to launch so you can change two numbers is a bad trade. The image resizer takes a file and two numbers and hands the result back about a second later.
How it works
- Drop a JPG, PNG, WebP, GIF, or BMP into the upload box. The original dimensions appear under the preview.
- Type the width you want. With the ratio lock on, the height is filled in for you. Switch to percentage mode if you would rather scale by half or by 150%.
- Pick JPEG, PNG, or WebP, check the estimated file size, and download.
Why the aspect-ratio lock is on by default
A 4000 by 3000 photo has a 4:3 shape. Force it into a 1000 by 1000 box and every face in it gets 33% narrower. That squash is the most common way a resize goes wrong, and a small preview hides it well enough that people ship it.
With the lock enabled, typing 1000 into the width field sets the height to 750 without you doing arithmetic. Turn the lock off when you genuinely want a different shape, and then reach for the crop tool instead if what you actually wanted was to keep part of the frame rather than distort all of it.
Shrinking is safe, enlarging is not
Going down in size throws pixels away. The browser averages neighbouring pixels as it draws, and the result looks as sharp as the original at the smaller size. That is why a 4000 pixel phone photo scaled to 1200 for a blog post looks fine.
Going up is a different story. There is no extra detail hiding in the file, so the browser interpolates: it guesses the in-between pixels from the ones it has. Edges soften and text goes mushy. Past roughly 200% the softness is obvious on any photo with fine texture. If you need a bigger version, start from a bigger source. The enlarge tool covers the upscale case when a bigger source is not available.
The file size number updates as you type
Most resizers tell you the dimensions and leave the file size as a surprise. This one encodes the result each time a setting changes and reports the real byte count, so the number next to "Estimated file" is what lands in your downloads folder.
That makes the format choice concrete. A 1200 by 800 photo saved as PNG might be 1.8 MB while the same pixels as WebP at 90% quality come in under 200 KB. If a form has a 500 KB ceiling, you can see which combination clears it before you commit. For heavier size reduction on images you do not want to shrink, the image compressor works the quality axis instead of the dimension axis.
Nothing leaves your machine
All of it happens on a canvas element. The browser decodes the file, redraws it at the target size, then encodes that canvas back into a blob. No request carries the image anywhere. Turn off your network after the page loads and it still works, which is a reasonable thing to want when the photo is a passport scan or a contract.