Compress Images

Hit an “under 200 KB” limit without guessing at quality numbers

Compressing a photo usually means nudging a quality slider until the size looks right. This tool has that slider too, but you can also type in the size an upload form demands and it finds the best quality that fits underneath. A suitable encoder for each format runs inside your browser, and you can process a whole batch at once.

A closer look

The standard mode works with “Output” and “Quality” (10 to 100, default 75). With “Keep original format (smart)”, JPGs are re-encoded with the MozJPEG encoder, while PNGs go through OxiPNG, which rebuilds the compression without changing a single pixel, so the quality slider does not apply to them. WebP uses the browser’s built-in encoder and AVIF a separate one; AVIF gives the smallest files but is the slowest. The JPG, PNG and AVIF encoders download once, the first time you use them. If recompressing in the same format would make a file bigger, the original is kept and marked “kept original (already optimal)”.

Tick “Hit a target file size” and enter something like 20KB or 1.5MB (no unit means KB, and 1 KB is 1,024 bytes). The tool tries quality 10 and 100 first, then keeps halving the gap, choosing the highest quality under the target within at most seven encodes. If even quality 10 is too big, it does not quietly hand you a larger file; the row is flagged as missing the target. Only when “Shrink the image too, if needed” is also ticked does it reduce the width and height and try again, and the result says by how much. Saving as JPG fills transparent areas with white, and re-encoding to JPG, WebP or AVIF drops EXIF data such as the shooting location.

How to use it

• Drop images onto the page or press Choose files. JPG, PNG, WebP and AVIF can be mixed in one batch.
• Set “Output” and “Quality”, or, if a form sets a limit, tick “Hit a target file size” and type the number into Target size.
• Press Compress. Each row shows the original size, the new size and the percentage saved.
• A single file downloads automatically. With several, press Save on each row or Download all. A file kept in its original format also keeps its original name, so check where it lands.

When it helps

Common snags

Tip When a whole batch has to meet one standard, test your quality or target on a single image and look at the result before adding the rest; it saves redoing the entire set.