Resize images by pixels, percentage or preset
Set new dimensions for one photo or a whole batch, with clean edges and no upload.
- Processed on your device. Your photos are never uploaded. How we know
- Free, no sign-up, no watermark
Drop images to resize
Drop files, paste with Ctrl+V, or choose them from your device.
PixWrench’s code runs on your device. We don’t receive your files, file names or their contents.
PixWrench’s code runs on your device. We don’t receive your files, file names or their contents. What happens to your files
How to resize an image to exact pixel dimensions
Most photos straight off a phone are far wider than any screen will show them. Resizing cuts the pixel count, which also cuts the file size, and gives you the exact dimensions a website, marketplace listing or profile picture slot asks for.
Type a width, a height or both, scale everything by a percentage, or choose a preset from the sizes collected in our social media image size guide. If you need a particular shape rather than a size, the crop tool lets you choose exactly which part of the picture stays.
- 1
Drop in your images
Add one picture or many. JPG, PNG, WebP, AVIF and HEIC are all accepted, and sideways phone photos are turned upright first.
- 2
Pick the new size
Enter pixels with the lock on to keep proportions, choose a percentage, or select a preset and decide how it should fill the frame.
- 3
Choose a format and save
Keep the original format or switch to JPG, PNG or WebP, then download each file or everything in one zip.
What this tool does
- Resize by width and/or height in pixels, with the aspect ratio locked or free
- Resize by percentage
- Social and web size presets
- Crop to fill, fit inside with a background color, or stretch
- Don’t enlarge option protects small images from upscaling
- Lanczos3 resampling in linear light with premultiplied alpha
- Save as the same format, JPG, PNG or WebP
- Batch resizing with a single zip download
A 1600 × 1200 photo resized three ways
Our 1600 × 1200 test photo is a 399 KB JPG. We resized it with the same Lanczos3 and MozJPEG builds the tool uses (quality 90, measured in Node with our script measure-t1.mjs).
| Setting | Result | File size |
|---|---|---|
| Width 1080 px, aspect locked | 1080 × 810 | 108 KB |
| 50% | 800 × 600 | 60 KB |
| 1080 × 1080, crop to fill | scaled to 1440 × 1080, then 180 px trimmed from each side | depends on content |
The arithmetic behind “aspect locked” is simple: the new height is the old height times new width over old width, so 1200 × 1080 ÷ 1600 = 810. A 4032 × 3024 phone photo set to 1080 wide lands on the same 1080 × 810.
Why the edges stay clean
Shrinking an image means deciding what each new pixel should be from a neighborhood of old ones. PixWrench uses a Lanczos3 filter, which weighs a wider neighborhood of source pixels than simple averaging does. It runs in WebAssembly via the open-source jSquash project.
Two quieter choices matter too. The math is done in linear light rather than on the gamma-encoded values stored in the file, so bright and dark details blend the way light actually mixes instead of turning muddy. And transparent images are processed with premultiplied alpha, which stops the hidden color of invisible pixels bleeding into the visible ones; that bleed is what causes dark halos around cut-out logos in cruder resizers.
Lossy output is saved at quality 90, high enough that the resize, not the encoder, decides what you see.
Crop to fill, fit inside or stretch?
A preset fixes both width and height, so a photo with a different shape has to give somewhere. You choose where:
| Option | What happens | Good for |
|---|---|---|
| Crop to fill | Scales until the frame is covered, then trims the overflow evenly from both sides (centered) | Profile pictures, thumbnails |
| Fit inside with background | Scales until the whole picture fits, then fills the empty bands with a color you pick | Product shots, anything that mustn’t lose an edge |
| Stretch | Forces the exact size, distorting proportions | Rarely; textures and test patterns |
Example: fitting our 1600 × 1200 photo inside 1080 × 1350 gives a 1080 × 810 picture, leaving 540 px of the 1350 px height for the background color.
Pixels, not DPI, decide the size on screen
Screens care only about pixel dimensions. The DPI number stored in a file is a printing hint and doesn’t change how many pixels there are. If you are preparing something for paper, our DPI versus pixels guide shows how many pixels a given print size needs.
Good to know
- Upscaling can’t invent detail. With Don’t enlarge on, images already smaller than the target are left at their size.
- Resizing reduces pixels; for an exact KB limit, run the result through the image compressor afterwards.
- Crop to fill always trims from the center. If the subject is off to one side, crop by hand first.
- Huge sources (over 50 megapixels on a computer, 24 MP on a phone) trigger an offer to scale them to 6,000 px on the long edge first, so your browser doesn’t run out of memory.
What happens to your files
Processed on your device. Your photos are never uploaded. PixWrench’s code runs on your device. We don’t receive your files, file names or their contents.
Your photos are decoded, resampled and re-encoded inside this tab using WebAssembly, and the resized copies are created on your device. Nothing from the pictures is sent to us. Your size, mode and format choices are remembered in your browser’s local storage, but the images themselves are never kept.
Separate from the tool, the page loads ad and analytics scripts; our privacy policy lists them.
Related tools and guides
Questions people ask
How do I resize an image without stretching it?
Keep the aspect lock on and enter only a width or a height. For a preset with a different shape, choose crop to fill or fit inside with background, never stretch.
Will resizing reduce the file size?
Usually by a lot. In our test, going from 1600 × 1200 to 800 × 600 took a 399 KB JPG down to 60 KB at quality 90.
Can I resize many photos at once?
Yes. Every image in the batch gets the same setting, and you can download them together as a zip.
Can I make an image bigger?
You can, by turning off Don’t enlarge. The result has more pixels but no extra detail, so it will look softer.
Does resizing keep transparency?
Yes, when you save as PNG, WebP or the original format if it supports transparency. Saving as JPG fills transparent areas with a background color.
How do I change the DPI for printing?
DPI is a print setting, not a pixel count. See the DPI and pixels guide for the pixels a print needs.
Sources and review
- MDN: Using responsive images in HTML
- jSquash: WebAssembly image codecs and resize (GitHub)
- MDN: Image file type and format guide
Page reviewed by the PixWrench team · How it works · Changelog · Report a problem