LazyTools

🔒 Every tool runs in your browser — the files and values you enter are never uploaded to any server. How it works

📏 Image Resizer

Resize to exact pixels — aspect ratio locked by default so nothing gets squashed — and download, all without the image leaving your device.

Rate this tool:
Anonymous — no account, no identifier

How the image resizer works

The image is redrawn at the target dimensions on a canvas with high-quality resampling enabled, then re-encoded in your chosen format. The aspect-ratio lock recalculates the other dimension as you type, because independent width/height edits are how images get visibly stretched. Downscaling discards pixels (fine); upscaling invents them (soft) — the tool tells you which you're doing.

Resolution advice that saves storage: screens are the destination for most images, and a 4000-pixel-wide photo shown in an 800-pixel column wastes 25× the pixels. Resize to roughly the largest display size you need (retina = 2× the CSS size), then compress — the combination routinely cuts files by 90%+.

Frequently asked questions

How do I resize without distorting the image?

Keep the aspect-ratio lock on: set one dimension, and the other follows automatically. Distortion only happens when width and height are changed independently to a different ratio than the original.

Can I make an image bigger?

You can set larger dimensions, but upscaling cannot add detail that was never captured — results look progressively softer. It's acceptable for modest bumps (up to ~1.5×); for serious enlargement you'd want a dedicated AI upscaler.

What size should images be for the web?

Match the largest size they'll display: full-width hero images ~1600–2400px wide, content images ~800–1200px, thumbnails 300–400px. Double the CSS pixel size for sharp rendering on high-DPI ("retina") screens.

Does resizing reduce file size?

Dramatically — file size scales roughly with pixel count, so halving both dimensions cuts pixels (and typically bytes) by ~75%. Resizing down is the single most effective image "compression" step.

Is the image uploaded to resize it?

No — the canvas API resamples on your device. Nothing is transmitted, and there's no watermark or size cap beyond your device's memory.

Related image tools

From the blog