How to Resize an Image to Exact Dimensions (or a Target File Size)

Q: How do I resize an image to an exact pixel size?

Open [resize](/resize), enter the exact width and height in pixels, keep aspect lock on (or off if you intend to stretch), and download.

2026-06-12

Short answer: To get an image to an exact width and height, use ToolKoala's resize tool — type the pixel dimensions you need, hit resize, and download. It runs in your browser, so the photo never uploads. The one thing people mix up: resizing changes dimensions (pixels), not file size (KB). If a form is rejecting your image for being "too large," you might actually need to compress it, not resize it.

Pixels vs percentage vs aspect-ratio lock

When you resize, you're choosing how to specify the new size:

Exact pixels: "make it 600 × 600." Use this when a form, avatar, or print spec demands precise dimensions.
Percentage: "make it 50% smaller." Handy when you don't care about exact numbers, just "shrink it a bit."
Aspect-ratio lock: keep width and height proportional so nothing stretches. Leave this on unless you specifically want to squish the image — turning it off lets you force, say, 600 × 400 even if the original was square, which distorts faces and text.

Steps in the browser

Open resize and add your image.
Enter the target width and/or height in pixels (or switch to percentage).
Keep "lock aspect ratio" on so it doesn't stretch — type one dimension and the other follows.
Resize, then download the result. Your original file stays as-is.

Want to prove it stays private? Open DevTools → Network before you start. No upload request fires; everything happens locally.

Resizing vs compressing — pick the right one

This is the part that wastes people an afternoon:

"It needs to be 300 × 300 px" → that's resizing. Use this tool.
"It needs to be under 200 KB" → that's compression. Shrinking pixels helps a little, but the real lever is quality/format. Use compress to hit a target file size.
"I need a square crop, not a squish" → don't distort by unlocking the ratio; use crop to cut to the right shape first, then resize.

A note on quality: shrinking an image is basically free — it always looks fine. Enlarging is where quality dies, because you're inventing pixels that weren't captured. If you genuinely need a bigger image, don't just resize up; use image upscale, which uses smarter interpolation.

Common needs this covers: passport/visa photos at exact px specs, forum and Discord avatars, "max 1920px" upload limits, and thumbnails.

Alternatives, honestly

Preview (macOS) / Paint (Windows) — free: Both do "Image Size" with exact pixels. Totally fine, already installed, no upload.
Photoshop (~$23/mo): Image → Image Size is precise and adds resampling control, but it's a subscription for a task a free tool handles.
Online resizers that upload: Fast, but they send your photo to a server. For anything personal, skip them.

FAQ

How do I resize an image to an exact pixel size? Open resize, enter the exact width and height in pixels, keep aspect lock on (or off if you intend to stretch), and download.

How do I resize an image to a specific KB or MB? Resizing dimensions only loosely affects file size. To hit a target like "under 200 KB," use compress instead, which adjusts quality and format.

Will resizing make my image blurry? Shrinking won't. Enlarging will, because there's no extra detail to add — for that, use image upscale.

How do I resize without stretching the image? Keep the aspect-ratio lock on. If you need a different shape entirely, crop it first, then resize.

— Milo 🐨