Image Resizer
Resize an image to an exact width and height, with optional aspect-ratio lock.
What is Image Resizer?
Image resizing is the process of changing an image's pixel dimensions, its width and height in pixels, to a different target size. Downscaling reduces the number of pixels and usually the file size, while upscaling increases them, though it cannot recover detail that was not captured in the original. Keeping the aspect ratio locked ensures the width and height scale together so the image is not stretched or squashed, whereas unlocking it allows an exact target size at the cost of visible distortion. Resizing is one of the most common image operations because screens, layouts, and performance budgets all expect images at specific dimensions rather than whatever the camera originally produced.
How to Use Image Resizer
- Drag an image onto the drop zone, or click it to choose a file — its original dimensions appear once it loads.
- Type a new width or height. With "Lock aspect ratio" on, the other field fills in automatically so the image isn't stretched.
- Turn the lock off if you specifically need an exact width and height, distortion included.
- Check the live preview and new dimensions, then click "Download" to save the resized image.
Examples
Resize to a fixed width, ratio locked
Input: 3000×2000 photo, width set to 1200
Output: 1200×800 — height derived automatically
Resize to an exact size, ratio unlocked
Input: 1600×900 banner, set to 1200×630
Output: 1200×630 — used exactly as entered
Common Mistakes
- Unlocking the aspect ratio without meaning to, then wondering why a resized photo looks squashed or stretched.
- Upscaling a small image expecting new detail to appear — resizing up can't recover resolution that was never captured.
- Resizing repeatedly (resize the resized output, again and again) — each pass re-samples the image and can accumulate visible softness; resize once from the original source when possible.
Why Use This Tool
- Runs fully client-side via the Canvas API — no upload, no file size limit from a server.
- Aspect-ratio lock prevents accidental stretching with one toggle.
- Live preview and new dimensions shown before you download anything.
- Works with JPEG, PNG, and WebP source images.