Image Resizer — Change Photo Dimensions by Pixels or %

Resize a photo to exact pixel dimensions or a percentage, with an aspect-ratio lock that fills in the matching side so nothing stretches. Hit upload size limits fast.

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When to use it

Shrinking a 12-megapixel phone photo to a 1200px-wide web image.
Making a square avatar fit a 400x400 profile-picture requirement.
Getting an image under a form's maximum-dimension upload limit.
Producing a small thumbnail from a large product shot for a listing grid.

Features

Set width and height in pixels
Resize by percentage of the original
Optional aspect-ratio lock auto-fills the other side
Preview the new dimensions before saving
Download the resized image

About Image Resizer

Image Resizer changes the width and height of an image by redrawing it on an HTML canvas at the size you specify, in pixels or as a percentage of the original. With the aspect-ratio lock on, typing one dimension automatically sets the other so the picture keeps its proportions and never looks squashed. It is the quick fix for hitting an avatar or upload size cap, producing a thumbnail, or shrinking a camera photo that is far larger than a page needs.

How to use this tool

Upload an image.
Enter the width and/or height.
Keep the ratio locked to avoid stretching.
Download the resized image.

Examples

Downscale a camera photo to a web width

Input

Original: 4000 x 3000 px · Set width: 1200 · Lock ratio: on

Output

Resized: 1200 x 900 px (same 4:3 proportions)

With the lock on, setting the width to 1200 fills the height to 900 automatically.

Resize by percentage

Input

Original: 1500 x 1000 px · Scale: 50%

Output

Resized: 750 x 500 px

Percentage scaling keeps the ratio without doing the pixel math yourself.

Tips & gotchas

Keep the aspect-ratio lock on for photos; only unlock it when you deliberately want to stretch or squash the image.
Downscaling looks clean, but enlarging past the original size cannot invent detail, so it softens — start from the largest copy you have.
Resizing changes pixel dimensions, not necessarily file weight; run the result through an image compressor if you need a smaller file size too.
Resize JPEG/PNG and re-export as the same type; for photos you can also export to WebP afterward for a smaller file at the same dimensions.

Specifications

Resize by	Exact pixels or percentage of original
Aspect ratio	Lockable — auto-fills the matching dimension
Formats	JPEG, PNG, WebP
Engine	Browser canvas redraw

This tool runs in your browser. Your files and text are not uploaded to our servers, and we do not store your input.

Frequently asked questions

Will resizing distort my image?+

Not if you keep the aspect ratio locked. Unlock it only when you intentionally want to stretch the image.

Can I make an image larger?+

Yes, but enlarging beyond the original size can look soft because no new detail can be added. Start from the highest-resolution copy you have.

Does resizing also reduce the file size?+

Usually yes, since fewer pixels mean less data, but it is not guaranteed for every format. To target a specific file size, resize first and then compress the result.