How to Resize Images Online

Resizing vs. compressing

These two terms get used interchangeably, but they do different things. Resizing changes the pixel dimensions of an image (say, from 4000×3000 down to 1200×900). Compressing keeps the same dimensions but re-encodes the pixel data to take up less file space. For the biggest size reduction with the least visible quality loss, you generally want both — resize down to the dimensions you'll actually display, then compress on top of that.

Why resize before uploading

Modern phone cameras capture images far larger than almost any website or app will display them at. A profile photo displayed at 200×200 pixels doesn't need to be a 4000×3000 pixel file — the browser would just scale it down anyway, wasting bandwidth and load time in the process. Resizing before upload fixes this at the source.

What size should you use

• Profile photos / avatars: 400-800px on the longest side is plenty
• Blog post images: 1200-1600px on the longest side covers virtually all display contexts
• Large hero/banner images: up to 2000px on the longest side for full-width desktop banners
• Print: resizing rules don't apply the same way — print needs much higher resolution and is a different consideration entirely

Keeping the aspect ratio

Always resize proportionally (locking width and height together) unless you specifically want to crop or stretch an image — stretching distorts faces and objects in an obvious, unflattering way. Good resize tools calculate the second dimension automatically once you set one.

Try it yourself

ToolFlight's Image Compressor automatically resizes any image over 2000px on its longest side as part of compression, so oversized photos are handled for you without an extra step.