Image Resizer

An image resizer changes the pixel dimensions of a photo or illustration — trimming an 8K camera RAW down to a 1080×1080 Instagram post, scaling a logo for a retina hero banner, or fitting an attachment under a strict inbox size cap. Because most modern pipelines ship images directly to social platforms, CMSes, or email, resizing is usually the last step before publishing. Do it well and the image looks sharp; do it badly and you end up with artefacts, file-size bloat, or a blurry upload that dilutes your brand.

Our resizer runs entirely in your browser. When you drop an image on the page, it is decoded with createImageBitmap and drawn into an HTML canvas element that the browser rasterises at the new dimensions. Photos never leave your device. That matters for client work, personal photos, screenshots of sensitive UIs, and anything you would not want sitting on a third-party server even briefly. Batch processing works the same way: every image in the queue is resized locally, then zipped with JSZip and handed back to your download folder.

Dimensions matter more than you might think. For Instagram feed posts, 1080×1080 square is the sweet spot; Stories and Reels want 1080×1920; a Twitter header is 1500×500; YouTube thumbnails want 1280×720; LinkedIn banners sit at 1584×396; and Facebook covers are 820×312 on desktop, a slightly different crop on mobile. We ship all of these as one-click presets so you do not have to memorise them.

Format choice is a trade-off. JPEG gives the smallest files for photos but uses lossy compression, so every re-save degrades quality a little. PNG is lossless, so it preserves every pixel — use it for screenshots, logos, and images with transparency. WebP is the modern default for the web: Google-backed, roughly 30% smaller than JPEG at the same quality, and now supported by every evergreen browser. We default to the original format so nothing changes unless you want it to.

Quality for lossy formats (JPEG and WebP) is controlled by a slider from 30% to 100%. For photos, 85–90% is visually indistinguishable from 100% while cutting file size roughly in half. For graphics with hard edges, stay above 90% to avoid colour banding. And remember that quality compounds: if an image has already been saved as a low-quality JPEG, resaving at 95% will not recover the lost detail.

A practical workflow note: upscaling — making an image bigger — always introduces blur, because pixels are interpolated from their neighbours. If you need a bigger version of a small image, go back to the source (a higher-resolution export, a vector file, or a fresh photo). Downscaling, by contrast, is near-lossless for photos and produces clean, crisp output at any target size.

1. Upload images. Drag them onto the drop zone or click Choose images. You can add as many as you like in one session.
2. Set dimensions per image. Edit width or height directly, or use one of the social-media presets to apply the same size to every image in the queue.
3. Lock or unlock aspect ratio. The padlock next to each pair keeps the original ratio. Unlock to distort intentionally.
4. Choose output format. Keep original, or convert to JPEG, PNG, or WebP.
5. Tune quality. For JPEG and WebP, drop the quality slider as low as you can without visible artefacts — usually 85–90% works.
6. Download. Single images download straight to your folder; batches are packaged into a ZIP.

• Batch resize with aspect-lock per image.
• Six social-media size presets built in.
• Format conversion between JPEG, PNG, and WebP.
• Quality control for lossy formats.
• ZIP download for batches.
• 100% local — images never leave your browser.
• No file-size limit other than your device's memory.