Compress Image

How browser-side compression works

This tool compresses images using the image decoder and canvas encoder already built into your browser. Your file is read into memory, decoded to a bitmap, then re-encoded as JPEG at progressively lower quality until the result fits your target size. The whole loop runs on your device's CPU, which is why it is fast and why no upload ever happens.

Server-based compressors need to move your photo to their machines, process it, and send it back — costing time, bandwidth and privacy. Browser-side processing removes that entire round trip. For sensitive documents (IDs, medical forms, financial records) it is the difference between keeping the file private and handing it to a third party you know nothing about.

The technical trade-off is minimal. Modern browser encoders produce JPEG output on par with native tools, and the size-targeting search guarantees the result fits your limit. The one constraint is your device's memory: files up to 50MB per image are supported, which covers every common photo format from any current phone or camera.

Choosing the right target size

Pick your target from the actual limit you are trying to satisfy, not from guesswork. If a form says 100KB, use the 100KB tool rather than compressing harder — every tool stops as soon as it fits, so targeting 20KB for a 100KB form only throws away quality for nothing. When no limit is stated, 200KB is a sensible default for photos on the web, and 100KB for thumbnails and avatars.

A common misconception is that smaller files always mean worse quality. Compression quality depends on the ratio between image content and size budget: a 1500-pixel photo at 1MB is barely compressed at all, while the same photo at 20KB must shrink drastically. Match the tool to the requirement and the quality follows.

If you are compressing for a website you control, check what dimensions the page actually displays. Serving a 4000-pixel image for a 400-pixel slot wastes the size budget on pixels nobody sees; resize first, then compress, and the same KB limit buys visibly better quality.

Which image formats can you compress?

The tool accepts JPG, PNG and WebP files on every platform, and HEIC photos on Safari and iOS. Output is always JPEG, because JPEG reaches the smallest file size at a given visual quality for photographs — which is exactly what a size limit demands. PNG files with transparency get a white background during conversion, so crop anything you need to keep transparent before compressing.

If your source file is a PNG screenshot rather than a photo, expect the JPEG conversion to change how crisp small text looks at very low quality settings. For a any target size target this rarely matters, because the tool keeps quality as high as the size budget allows. Screenshots with large flat-color areas also compress surprisingly well, since JPEG handles uniform regions efficiently.

HEIC photos from iPhones are handled automatically on Safari and iOS. On other browsers, HEIC support depends on the underlying engine; if your HEIC file is rejected, convert it to JPG first in your phone's share sheet or photos app — the quality cost of that extra step is negligible compared to the compression itself.

A practical rule: start with the largest, cleanest original you have. Compressing an already-compressed image compounds quality loss — a fresh export from your phone or editor gives the best result at any target size.