Compress images in bulk

A size limit beats a quality setting for a batch

Picking one quality for a folder produces wildly different file sizes, because a busy photograph and a flat graphic compress nothing like each other at the same setting. If the reason for compressing is a limit — an upload form, an email attachment, a page-weight budget — then set that limit instead.

Each image is then searched individually for the highest quality that still fits underneath it. A simple picture keeps more quality than a complicated one, every file lands under the number, and nothing has to be redone because one straggler came in over.

Why there is no file limit

Free tiers elsewhere cap at twenty or fifty files for a straightforward reason: every image costs the operator processing time on hardware they rent. Here the processing happens on your own machine, so there is nothing to meter. The limit is your device's memory, not a number chosen to sell an upgrade.

Some files will not get smaller, and that is correct

A photo straight from a camera or phone typically loses 60–80% with no visible change, because it was saved at a conservative default. An image that has already been compressed has had that slack removed, and running it through again mostly adds artefacts. Where re-encoding would not produce a smaller file, the original is handed back unchanged rather than a marginally larger one — a compressor that returns a bigger file has failed, whatever its settings said.

Resizing usually beats compressing

If the images are larger than they will ever be displayed, reducing the dimensions removes far more weight than any quality setting, and costs nothing visible. Halving the width and height leaves a quarter of the pixels before compression is even considered. For a folder destined for a website or an email, resize first and compress second — the two together do more than either alone.