Resize images to exact pixel dimensions
Set an image to an exact pixel width and height — handy for upload limits, thumbnails, avatars, banners and platform-specific size requirements. Lock the aspect ratio to scale proportionally, or unlock it to stretch to precise dimensions. It runs entirely in your browser.
How it works
When you load an image its native dimensions are read and pre-filled. With Keep aspect ratio on, editing one dimension recomputes the other from the original ratio, so nothing distorts. On Resize, the tool creates a <canvas> at your target size, sets imageSmoothingQuality = "high", and draws the source scaled to fit with ctx.drawImage(img, 0, 0, width, height). It exports with canvas.toDataURL — PNG is lossless, while JPG and WebP use your quality slider (JPG is filled white first since it has no alpha).
Worked example
A 4032×3024 phone photo that a form requires at 800px wide: load it, type 800 into Width with aspect ratio locked — Height auto-fills to 600 — pick JPG at 90%, and download. The downscale is sharp thanks to high-quality smoothing. The original file is unchanged.
Common target dimensions
| Platform / use case | Target size |
|---|---|
| Twitter / X profile photo | 400×400 |
| LinkedIn profile photo | 400×400 |
| Facebook cover photo | 820×312 |
| Instagram square post | 1080×1080 |
| YouTube thumbnail | 1280×720 |
| Web full-width banner | 1920×600 |
| Email header image | 600×200 |
| Avatar / profile icon | 256×256 |
| App store screenshot (iOS) | 1290×2796 |
Downscaling vs. upscaling
Downscaling (making an image smaller) generally produces excellent results because the browser engine averages many source pixels into fewer output pixels. The imageSmoothingQuality = "high" setting uses a bicubic-like algorithm that preserves edges well.
Upscaling (enlarging beyond the original) cannot add detail — it interpolates between existing pixels, which produces a softer result. If you need a large print-ready image, start from the highest-resolution source you have. Upscaling is still useful for pixel art (where you want nearest-neighbor-style scaling) but that requires a dedicated tool that disables anti-aliasing.
Choosing an output format
- PNG — lossless, best for screenshots, logos, and anything with sharp edges or transparency. Larger file size than JPG for photos.
- JPG — lossy compression, best for photographs. Quality 80-90% is usually indistinguishable from the original at normal viewing size and produces a much smaller file.
- WebP — modern format supported by all current browsers. Offers both lossless and lossy modes, and is typically 25-35% smaller than JPG at equivalent quality.
The resize runs entirely on your device using the Canvas API. Your images are never sent to any server — this matters for confidential, watermarked, or embargoed images that should not pass through a third-party service. The original file on disk is never modified; a new file is created for download.