Resizing sounds trivial until your photo comes out stretched, blurry, or cropped in the wrong place. A little understanding of pixels, ratio and DPI makes it foolproof.
Pixels vs. DPI — the thing everyone confuses
An image's real size is its pixel dimensions — say 4000 × 3000. DPI (dots per inch) only matters for printing: it tells the printer how many of those pixels to pack into each inch of paper. On a screen, DPI is irrelevant; only pixels count. So "make it 300 DPI" means nothing for web use — what a website needs is the right pixel width.
Set exact pixels or a percentage, keep the ratio locked, and download instantly — no watermark.
Open Resize ImageKeep the aspect ratio
Aspect ratio is the relationship between width and height. Change one without the other and your image stretches — faces go wide, circles become ovals. Always resize with the ratio locked so both dimensions scale together. If you need a specific shape (a square avatar, a 16:9 banner), crop to that ratio first, then resize — don't distort.
The right size for each use
| Use | Typical size |
|---|---|
| Full-width website hero | ~1920px wide |
| In-article image | ~800–1200px wide |
| Instagram post | 1080 × 1080px |
| Instagram story / Reel | 1080 × 1920px |
| YouTube thumbnail | 1280 × 720px |
| Print photo (6×4 in) | 1800 × 1200px @300 DPI |
For social, our Social Media Resizer has these presets built in so you don't have to memorise them.
Never upscale (much)
Making an image smaller is lossless-looking — you're throwing away pixels you don't need. Making it bigger invents pixels that were never there, so it gets soft and blocky. If you must enlarge, do it modestly and expect some quality loss. Better to start from the largest original you have.
Resize, then compress
The biggest web-performance win is a two-step move: resize to the pixel width you'll actually display, then compress. A photo shrunk from 4000px to 1200px and compressed can go from 5MB to under 200KB with no visible difference. See our guide on choosing the right format to squeeze it even smaller. Need an exact file-size target? The Image Size Reducer hits "under 100KB" for you automatically.