Image Resizer
Resize an image to exact pixel dimensions with aspect-ratio lock and Lanczos3 resampling, then save as JPEG, PNG or WebP. Runs in your browser.
Your inputs and files stay in your browser
Original Image
Drag and drop a file here
or choose a file from your device
Choose an image first.
The resized image appears here.
Fit scales both images into one frame, so they look the same size. Switch to 1:1 to see their real pixel dimensions.
On this page
Resize an image to exact pixel dimensions with an optional aspect-ratio lock and download it as JPEG, PNG or WebP. The image is processed in your browser and never uploaded.
Detailed Functionality
After you pick a file the tool reads its original size and fills Width (px) and Height (px). With Maintain Aspect Ratio on, changing one side recalculates the other from the original proportions; with it off you can enter any size and the image is stretched to fit. Resampling uses the Lanczos3 filter, which keeps downscaled images sharp.
The output Format is preset from the file extension (JPG stays JPEG, PNG and WebP stay as they are, anything else becomes PNG) and can be changed. JPEG and WebP are saved at quality 90 (WebP through the browser's lossy encoder when available), PNG is lossless. Inputs can be PNG, JPEG, WebP, GIF, BMP, ICO, TIFF or TGA; formats the browser cannot display are decoded by WebAssembly for the preview.
Sizes must be whole positive numbers, at most 16384 px per side and 64 megapixels in total; invalid values are flagged before any work starts. Resizing runs in a Web Worker and can be cancelled. Files are named <name>_<width>x<height>.<ext>.
Practical Examples
Half size: a 1920×1280 photo with width 960 and the lock on becomes 960×640; as WebP it weighs 46.94 KB and downloads as photo_960x640.webp.
Exact square: turn off Maintain Aspect Ratio and enter 512 × 512 — the image is stretched, not cropped.
Too large: a width of 20000 is rejected with “Dimensions are too large: at most 16384 px per side and 64 megapixels in total.”
TGA input: a 640×480 .tga texture resized to width 320 gives a 320×240 PNG.
How to Use This Tool
Choose an image
Click Choose file or drop an image onto the zone. The original dimensions appear under Original Image.
Set the new size
Enter Width (px) or Height (px). Keep Maintain Aspect Ratio on to preserve proportions.
Pick a format and resize
Choose JPEG, PNG or WebP in Format and click Resize. Use Cancel to stop a long job.
Download
Check the new size under Result Info and click Download.
Tips and Best Practices
- Downscaling keeps quality; upscaling cannot add detail and makes the image softer.
- Keep the aspect-ratio lock on unless you really want to stretch the picture.
- For web thumbnails WebP or JPEG keeps files small; use PNG for screenshots and graphics with transparency.
- Very large targets need a lot of memory: 64 megapixels of RGBA is about 256 MB in the browser.
- Metadata such as EXIF and GPS is not copied to the resized file.