Free Converter
Image Resizer
Resize images to any dimensions. Lock aspect ratio to avoid distortion. Export as PNG, JPG, or WEBP.
Drop your image here
Supports PNG, JPG, WEBP, GIF, and more
Or
Resize images to any dimensions. Lock aspect ratio to avoid distortion. Export as PNG, JPG, or WEBP.
Supports PNG, JPG, WEBP, GIF, and more
Image resizing changes the pixel dimensions of a bitmap, either smaller (downsampling) or larger (upsampling). The two operations are not equivalent. Downsampling discards pixel data; upsampling invents pixel data through interpolation. Downsampling produces a smaller, sharper image; upsampling produces a larger image but cannot recover detail that was not in the source. Knowing which direction you are going determines what to expect from the result.
This resizer runs in your browser using the HTML5 Canvas API. The source image is decoded into a canvas, drawn at the new dimensions using the browser's built-in resampling, and re-encoded in the original format (or your chosen output format). Quality settings affect lossy formats (JPEG, WebP). The output is identical to what canvas-based resizing produces in any web app.
For the highest-quality downsampling, the browser uses bilinear or bicubic interpolation depending on implementation. For upsampling, the same interpolation produces a smooth but soft result. Specialized AI upscalers (waifu2x, Topaz Gigapixel) produce sharper upscales but require dedicated tools.
Image dimensions affect file size, page load time, and platform compatibility. A 4000×3000 photo from a smartphone camera weighs several megabytes; resizing to 1920×1440 typically yields a file 4-6× smaller with no perceptible quality loss for screen viewing. Multiplied across many images on a page, this is a significant performance win.
Platform requirements also drive resizing. Profile photos at specific dimensions, marketplace images at maximum allowed sizes, social media previews at exact aspect ratios — each platform expects a specific size, and resizing locally is faster than fighting the platform's auto-resize.
Drop the image, set new dimensions, download.
Choose the right target dimensions before resizing — picking too small loses detail, too large wastes bandwidth.
The Canvas API resamples using the browser's built-in implementation. Most browsers use bilinear or bicubic interpolation; the exact algorithm varies but quality is comparable across modern browsers.
Output format depends on canvas.toBlob mime type. PNG preserves exact pixels with lossless compression. JPEG applies DCT-based lossy compression at the chosen quality. WebP supports both modes; lossy WebP at quality 80-85 is roughly equivalent to JPEG at quality 90.
Aspect ratio: the resizer locks aspect ratio by default to preserve proportions. Unlocking allows arbitrary stretching, which is rarely desired but useful for specific layouts.