How to Compress Many Images at Once, Free and Without Uploading

Lossy compression (JPG, WebP, AVIF) throws away detail the human eye barely notices, such as tiny colour variations in a sky or fine noise in shadows. The quality setting decides how aggressive it is. Lossless compression (PNG) keeps every pixel exactly and only packs the data more cleverly, so savings are smaller.

Resizing is also compression. A 4000-pixel-wide photo shown in a 800-pixel slot wastes about 25 times the pixels it needs. Cutting dimensions to the size you will actually display usually saves more than any quality slider.

For photos, choose WebP at quality 70-80, or JPG at 75-85 if the destination does not accept WebP. Below about 60 you start to see blocky edges and smeared texture; above 85 the file grows quickly with no visible gain.

For screenshots, logos and graphics with flat colour, keep PNG and only resize, or convert to WebP lossless-friendly settings at quality 90 or higher. Text and sharp edges show compression damage first.

If a form or portal asks for a maximum size such as 100 KB or 200 KB, use the "Max size per image" option. The tool searches for the highest quality that still fits, so you do not have to guess.

Typical phone and camera JPGs shrink by 50-80% when re-encoded at quality 75 and resized to a sensible width. PNG screenshots converted to WebP often drop by 60-90%. Images that were already optimised may barely change, and in that case the tool keeps your original instead of making it bigger.

Each row shows the before and after size and the percentage saved, and the summary adds up the whole batch, so you can see the real result before you download.

The images are decoded and re-encoded by your own browser using its built-in canvas engine. Nothing is sent to a server, so confidential documents, ID photos and unreleased product shots never leave your device.

Re-encoding also removes camera metadata (EXIF), including GPS location, which is a useful side effect before you post photos publicly.

Do not compress the same JPG over and over; every lossy pass loses a little more. Keep your originals and compress copies. Do not use JPG for images with transparency, because it will fill transparent areas with a colour. And do not rely on a single quality number for every image: a busy photo can take 70, while a smooth gradient may need 85 to avoid banding.