Numarly

Resize Image

Change an image's width and height, with an aspect-ratio lock.

Click to select an image, or drag and drop it here

JPG, PNG, WebP, and other image formats

What is it?

This tool resizes an image to an exact pixel width and height, entirely in your browser, with an optional aspect-ratio lock so the image doesn't stretch or squash.

Formula Explanation

The image is drawn onto a canvas sized to your target width and height, which scales every pixel to fit. When the aspect-ratio lock is on, changing one dimension automatically recalculates the other using the original image's width-to-height ratio, so proportions are preserved.

Example Calculation

A 1600 × 1200 image resized to a width of 800 with the aspect-ratio lock on automatically sets the height to 600, keeping the same 4:3 ratio.

How to Use

  1. Click the upload area or drag and drop an image onto it.
  2. Enter a target width and/or height in pixels.
  3. Leave "Lock aspect ratio" on to avoid stretching, or turn it off to set both independently.
  4. Click Resize & Download to save the result.

Benefits

  • Resizes images to an exact pixel size without installing any software.
  • Processes everything locally in your browser — images are never uploaded anywhere.
  • Aspect-ratio lock prevents accidental stretching or squashing.

Use Cases

  • Shrinking a large photo before attaching it to an email or form.
  • Resizing an image to fit a website's or app's required dimensions.
  • Preparing a profile picture or thumbnail at a specific size.

What Your Result Means

The downloaded image has exactly the width and height you entered, in the same file format as the original. Enlarging an image beyond its original size can make it look soft or blurry, since no new detail is created.

Tips

  • Keep the aspect-ratio lock on unless you specifically want to stretch the image.
  • Shrinking a photo is lossless in terms of proportions; enlarging it much beyond its original size will look blurry.
  • Check the displayed original dimensions first so you know what ratio you're working with.

Common Mistakes

  • Turning off the aspect-ratio lock and entering mismatched dimensions, which stretches the image.
  • Enlarging a small image far beyond its original size and expecting sharp results.
  • Entering 0 or a blank value for width or height.

FAQs

Are my images uploaded to a server?

No, all processing happens locally in your browser using the Canvas API — your images never leave your device.

Does resizing reduce file size too?

Usually yes, since fewer pixels generally means a smaller file, but for precise file-size control use the Compress & Convert Image tool.

Can I resize by percentage instead of exact pixels?

Not directly — calculate the target pixel dimensions from your original size and desired percentage (e.g. 50% of 1600×1200 is 800×600) and enter those.

What image formats are supported?

Any image format your browser can display, including JPG, PNG, and WebP — the downloaded file keeps the same format as the original.

Images are read and resized locally in your browser and are never uploaded to a server.

Last updated: August 1, 2026