Image Resizer
Resize PNG, JPG, and WebP images to exact pixel dimensions. Keeps the aspect ratio if you want.
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How to Use the Image Resizer
Upload your image, enter width and/or height in pixels. Use the lock icon to maintain aspect ratio. Download the result.
About This Tool
Social media platforms, e-commerce sites, and email services all have specific image dimension requirements — Instagram posts are best at 1080×1080 pixels, Facebook covers at 820×312, product photos on Amazon at 2000×2000. Uploading the wrong size leads to cropping, stretching, or poor display quality. This resizer lets you set exact pixel dimensions with an optional aspect ratio lock so your images are never distorted.
Typical jobs this handles: preparing a photo for LinkedIn where the platform's banner recommends 1584×396; shrinking a 12-megapixel DSLR JPG down to 1920×1080 for a presentation slide (dropping file size from ~4MB to ~500KB); scaling a product photo up to meet Amazon's 1000-pixel minimum on the long edge for zoom functionality. Each of these benefits from an aspect-lock to avoid cropping decisions the resizer shouldn't be making for you — dedicated tools handle that.
The resize uses the browser’s Canvas API via drawImage() with imageSmoothingQuality: 'high', which on modern Chrome and Safari uses a bicubic-style sampling kernel — the same algorithm Photoshop uses for its "Bicubic Smoother" setting. Firefox uses a slightly different bilinear-plus approach, but results are visually very close. One known limitation: extreme downscales (e.g., 4000×4000 down to 200×200 in one pass) can show aliasing because browser Canvas doesn’t do multi-pass box filtering. For best quality on large reductions, resize in two steps through an intermediate size — but for typical web-asset work this is rarely noticeable.
Compared to opening Photoshop or GIMP, this tool is about 10 seconds start-to-finish (pick file, type dimensions, download) and requires no install. Compared to online resizers that upload your image to their server, nothing leaves your device — files are loaded through the FileReader API, resized on a local Canvas, and exported via toBlob, all client-side.
Frequently Asked Questions
Is the Image Resizer a server-side service, or does it run in my browser?
It runs entirely in your browser. When you pick an image, it is loaded into a Canvas element and resized using native browser APIs (drawImage with the new dimensions). The output is generated from the Canvas via toBlob, which returns a local File object. No HTTP upload is ever triggered; the resized file is created directly in memory.
Which image formats does the Image Resizer accept and output?
The Image Resizer accepts PNG, JPG/JPEG, WebP, and BMP. The output format matches the input by default — a JPG stays a JPG, a PNG stays a PNG — which preserves transparency on formats that support it. If the input has an alpha channel and you export to JPG, the alpha is flattened onto a white background automatically.
Does the Image Resizer have a maximum input size?
No hard limit, but browser memory and Canvas dimensions are the real ceiling — most modern browsers cap Canvas at about 16384 pixels on either side, so ultra-high-resolution sources may need to be pre-scaled. For typical photos and web assets under 50MB the resizer works without issue. All work happens in your browser, so no server bandwidth or quota applies.
Will resizing make my image blurry?
Enlarging an image beyond its original dimensions (upscaling) will reduce sharpness because the browser must interpolate new pixels. Reducing dimensions (downscaling) generally preserves quality well. For best results, start with the highest resolution original available.
Can I resize multiple images at once?
This tool processes one image at a time. Upload your image, set the dimensions, download the result, then upload the next. For batch processing, consider using the command-line tool ImageMagick.
Created by The Toobits Team · Engineering & Editorial
Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.
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