How to reduce image file size without it looking worse
Most photos straight off a phone or camera are saved at very high quality, which means a lot of bytes the eye can't see. Re-encoding at a sensible quality throws away that invisible detail. That's why compressing a 4 MB photo to under 1 MB often looks identical on screen.
Start at High (90%). If the file is still too big, drop to Med (75%) and zoom into faces, text and smooth gradients like sky. Those are where compression shows first, as blocky patches or banding. Go to Low (50%) only for thumbnails and previews.
Which format compresses best?
Format matters as much as the quality slider. Here's how the three outputs compare for the same photo.
| Format | Compression | Best for | Watch out for |
|---|---|---|---|
| JPEG | Lossy, quality slider applies | Photos for email, forms, any website | No transparency; transparent areas turn white |
| WebP | Lossy, usually smaller than JPEG | Your own website, modern browsers and apps | Some older apps and upload forms reject it |
| PNG | Lossless, quality slider ignored | Screenshots, logos, graphics with sharp edges | Photos saved as PNG are often larger than the original |
Compress vs resize: when you need both
An image compressor makes the file lighter but keeps every pixel. If your photo is 4000 pixels wide and the page shows it at 1200, you're still shipping three times more pixels than needed. In that case, resize first with the image resizer, then compress the result. Together they usually beat any single image optimizer setting.
If a compressed file comes out larger than the original, the source was already well optimized. Lower the quality, switch to WebP, or just keep the original.
