Image | Edit

Resize images online

Set exact pixel dimensions or scale by percent in your browser, with aspect ratio locked by default.

Image resizer changes the pixel dimensions of an image while keeping aspect ratio and quality under control. It runs entirely in your browser without uploading the file. Image Resizer on DocTools helps you resize for Instagram, YouTube, Twitter and more, with no account needed.

Free to use
No signup
No uploads
Works offline

Why use Image Resizer

Locks aspect ratio to prevent stretch
Pick JPG, PNG, or WebP output
Batch dozens at a time
Files never leave your device

Resizing runs locally in your browser. Nothing is uploaded.

How to use Image Resizer

Add an image Drop or select your image file.
Set dimensions Enter target width or height (aspect ratio locks by default).
Download the resized image Save the result.

Benefits

Hit any size spec

Design systems, social platforms, and print all demand exact dimensions; the resizer nails them in one click.

Stop paying for extra pixels

Resizing before compression is the single biggest byte-saver for image-heavy pages.

Private and fast

Everything runs in the browser, so brand assets stay on your device.

Who it is for

Social media

Producing 1080x1080 posts from a landscape photo Outcome: Frames sized for the platform in seconds.

Developers

Generating responsive image variants for a build Outcome: Ready-made assets for srcset without a bundler plugin.

Print teams

Downsizing a hero shot to a spec sheet size Outcome: Files that pass DPI checks in the layout tool.

How it works

Image Resizer loads your image into memory, applies the change you requested to the underlying data rather than to a screenshot of it, and writes a fresh copy for download. Your original stays untouched on disk, and every step of Image Resizer happens inside your browser sandbox.

Frequently asked questions

Can I keep aspect ratio?

Yes. Lock the aspect ratio to prevent distortion when resizing.

Which formats are supported?

JPG, PNG, and WebP inputs; you can export to any of the three.

Which resampling algorithm is used?

Lanczos-3 by default for a sharp downscale. Bilinear is available for softer upscales.

Can I lock aspect ratio?

Yes. Lock is on by default; unlock to stretch to arbitrary dimensions.

What if I only set width or height?

The other dimension is computed to preserve aspect ratio automatically.

Does resizing degrade quality?

Downscaling looks crisp. Upscaling beyond source resolution invents pixels, so expect softness above ~150%.

Related tools

Instagram Story Maker | Design 1080x1920 stories with templates
JPG to PDF | Transform images into PDF documents
PNG to PDF | Convert PNG images into a PDF document

Last updated: 2026-07-09