Image Resizer
Resize images online for free. Set exact width and height in pixels, keep aspect ratio, and download instantly — no upload needed.
Click to choose a file or drag & drop here
JPG, PNG or WebP · resized privately on your device
Resizing changes an image’s pixel dimensions — the actual width and height. It is the most effective way to reduce file size, and it is what upload forms mean when they specify a maximum size in pixels.
This tool resizes to exact dimensions with aspect-ratio locking so nothing is distorted, using your browser’s canvas engine. No upload, no account, no watermark.
How to use the Image Resizer
Add your image
Drag it in or click to browse. The current dimensions are shown immediately.
Enter the target size
Set a width or a height in pixels. With the aspect ratio locked, the other dimension follows automatically.
Decide about the aspect ratio
Keep it locked unless you specifically need to stretch the image — unlocking distorts the picture.
Resize and download
The resized image downloads straight to your device.
Common size requirements
| Where | Recommended pixels |
|---|---|
| Instagram square post | 1080 × 1080 |
| Instagram story / Reel | 1080 × 1920 |
| YouTube thumbnail | 1280 × 720 |
| LinkedIn banner | 1584 × 396 |
| Facebook cover | 1200 × 630 |
| X / Twitter header | 1500 × 500 |
| Open Graph share image | 1200 × 630 |
| Favicon | 512 × 512 source |
| Website hero | 1920 × 1080 |
| Passport photo (US) | 600 × 600 at 300 DPI |
Aspect ratio, and why you should not unlock it
Aspect ratio is the proportion of width to height. Changing width and height independently stretches the image — faces widen, circles become ovals, and the result looks unmistakably wrong even to people who cannot say why.
When a target has a different ratio from your source, crop rather than stretch. Use the image cropper to take the right shape out of the picture first, then resize that to the exact pixel dimensions.
Never upscale if you can avoid it
Enlarging an image cannot add detail that was never captured. Software interpolates new pixels by guessing from neighbours, which produces softness and visible artefacts. A 400-pixel image scaled to 1600 will always look worse than a 1600-pixel original.
Downscaling, by contrast, is essentially free — discarding pixels loses nothing visible. Always keep and work from the largest original you have, and export smaller copies as needed.
Pixels, DPI and print
DPI is meaningless on screen — a display shows pixels, and a 1000-pixel image is 1000 pixels wide regardless of what DPI value is stored in the file.
DPI matters only for print, where it sets physical size. At 300 DPI, a 1800 × 1200 pixel image prints at 6 × 4 inches. To find the pixels needed for a print, multiply the inches by 300 — an 8 × 10 print needs 2400 × 3000 pixels.
Serving the right size on a website
- Match the display size. A 4000-pixel image in an 800-pixel column wastes bandwidth on every visit.
- Account for retina screens by exporting at roughly twice the CSS display width.
- Use `srcset` to offer several sizes and let the browser choose based on the device.
- Set width and height attributes so the browser reserves space and the page does not jump as images load — layout shift is a Core Web Vitals ranking factor.
- Resize before compressing. In that order the file size reduction is far larger.
Frequently asked questions
How do I resize without distorting the image?
Keep the aspect ratio locked and set only one dimension — the other adjusts proportionally. Unlocking it stretches the picture.
Are my images uploaded?
No. Resizing happens in your browser using its canvas engine, and your images never leave your device.
Can I make an image larger?
You can, but the result will be soft. Upscaling invents pixels rather than recovering detail — always work from the largest original available.
What is the difference between resizing and cropping?
Resizing scales the whole image to new dimensions. Cropping cuts away part of it to change the composition or ratio. Use the image cropper when the target shape differs from your source.
What size should a website image be?
Match the display size, roughly doubled for high-density screens. A full-width hero is typically 1920 pixels wide; a blog body image 800–1200.
Does resizing reduce file size?
Substantially. Halving both dimensions leaves a quarter of the pixels, which usually cuts the file size by 70% or more. Follow up with the image compressor for further reduction.
What does DPI mean here?
Nothing for screen use — displays render pixels. DPI only determines physical size in print: divide pixel dimensions by 300 for the printed size in inches.
Can I resize several images at once?
Add multiple files and each is resized to your target dimensions. With the ratio locked, images of different shapes will match on one dimension.
100% private. Files are processed on your device and never uploaded.
Instant results. No upload queue. Processing time depends on your device.
Free forever. No signup, no watermark, no paid tier.
Works everywhere. Use a modern browser on your phone or computer.
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Image Resizer is one of all the free tools on ToolNest. No account or subscription needed — anywhere in the world.