Getting under an upload limit
Most people land here because a form said no. A job portal wants a photo under 200 KB, a visa site caps uploads at 500 KB, or an email bounces because the attachments are too big. The size presets are built for exactly that: pick < 200 KB, < 500 KB or < 1 MB and the tool searches for the highest quality that still fits.
Which preset to start with
| Preset | What it does | Good for |
|---|---|---|
| Best (default) | Keeps your format, quality 78, longest side capped at 4,096 px | General sharing when you don’t want surprises |
| Smallest | WebP at quality 55, longest side 2,048 px | Website images, chat apps, slow connections |
| High quality | Keeps format, quality 90, no resizing | Portfolio shots where detail matters more than size |
| Lossless | PNG optimized with OxiPNG, pixels untouched | Screenshots, diagrams, logos |
| < 200 KB / 500 KB / 1 MB | Finds the best quality that fits under the limit | Forms and portals with a hard cap |
Changing any setting by hand switches you to Custom. Nothing is re-run until you press Apply, so you can adjust several things first.
Why some images barely shrink
- Photos saved as PNG. PNG is lossless, so a photo stored as PNG stays huge even after optimizing. Switching the output to JPEG or WebP is what makes the difference, often 80 to 90 percent smaller.
- JPEGs that were already compressed. Images downloaded from social media have usually been squeezed once. A second pass at a similar quality saves little and can add blockiness, so try a smaller size instead.
- Screenshots with text. Sharp edges are where lossy formats struggle. Lossless PNG or WebP keeps text crisp; lossy settings blur it before they save much.
Pixel size matters more than the quality slider
File size grows with the number of pixels. Halving the width and height leaves a quarter of the pixels, which usually cuts the file by more than any quality change you could make without visible damage. If your image will be shown at 1,200 px wide on a website, there is no reason to keep it at 4,000 px. Use the Max longest side box, or the image resizer if you need exact dimensions.
What happens to your photo’s hidden data
Compression rebuilds the image from its pixels, and the encoders used here (MozJPEG, libwebp, libavif and OxiPNG, running as WebAssembly in your browser) don’t write EXIF data. The camera model, the date and any GPS location stored by your phone are not in the downloaded file. Rotation is applied to the pixels first, so photos stay the right way up.
The files themselves are read and encoded inside this browser tab. They are not sent to Mewix or anyone else. You can confirm it in your browser’s network panel: the only requests are for the page and the encoder code itself.
Questions
How many images can I compress at once?
Ten per batch. Download them one at a time or all together as a ZIP, then press Compress more for the next ten.
Can I compress a GIF or a HEIC photo from an iPhone?
Yes for both, but they are saved in a different format. HEIC comes out as JPEG or WebP, and a GIF is saved as a still image of its first frame, so animation is lost.
Will the compressed image look worse?
At the Best and High quality presets, differences are hard to spot at normal size. Drag the compare slider over faces, text and skies, which are where compression shows first, and zoom in if you need to be sure.