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Image Resizer

This image resizer changes the pixel dimensions of a picture while keeping it entirely on your device. Enter exact width and height, use a percentage preset, and export as JPEG, PNG or WebP.

Your data is processed locally in your browser and is not uploaded to our server.

or drop an image here

JPEG · PNG · WebP · GIF · max 20 MB

How to use this tool

  1. 1 Choose or drop an image; its original dimensions appear automatically.
  2. 2 Enter a new width or height, or use a 25%, 50% or 75% preset.
  3. 3 Keep “Lock aspect ratio” on to derive the other side automatically.
  4. 4 Choose the output format and download the resized image.

Formula and calculation logic

Aspect ratio

New height = New width × original height ÷ original width

With the ratio locked, one dimension determines the other so the image is not distorted. Disable the lock to set both sides independently.

Percentage scaling

New dimension = Original dimension × percentage

A 50% preset halves both sides, producing an image with a quarter of the pixels. Percentages are rounded to whole pixels.

Worked example

Half-size photo

A 3000 × 2000 photo needs to be 1500 pixels wide for a web page.

  1. Set width to 1500
  2. Aspect ratio locked: height becomes 1000
  3. Export as WebP or JPEG

The resized image keeps the 3:2 ratio and has one quarter of the original pixels.

Exact thumbnail

A thumbnail must be 400 × 400 without distortion.

  1. Unlock the aspect ratio
  2. Set 400 × 400
  3. Crop afterwards if the subject is stretched

Resizing to a different ratio stretches the image. Use the cropper first when a square thumbnail must not distort the subject.

Edge cases and accuracy

Upscaling

Enlarging a small image cannot add real detail; it only interpolates. Start from the largest original you have.

Maximum dimensions

Canvas dimensions are limited by the browser and device memory. Very large values (above 10,000 px) may fail on mobile.

Transparency

PNG and WebP preserve transparency; JPEG replaces it with white. Choose a format that matches the image content.

Frequently asked questions

Does resizing reduce file size? +

Fewer pixels usually mean a smaller file, but the format and quality also matter. Use the image compressor to control both.

Will my image look stretched? +

Only if the aspect ratio is unlocked and both sides are set independently. Keep the lock on for proportional scaling.

Can I enlarge an image? +

Yes, but interpolation cannot restore missing detail. The result may look soft, especially at large enlargement factors.

Is the image uploaded? +

No. The image is decoded and redrawn in your browser and never leaves your device.

Which format should I export? +

Use WebP for the best size, JPEG for compatibility with photos, and PNG for screenshots, diagrams or transparency.