Bulk Image Converter
Convert many images to JPG, PNG or WebP at once and download them as a ZIP.
Processing: This tool runs entirely in your browser. Your input and any file you open stay on your device — nothing is uploaded to a server. Up to 100 images per batch; the practical ceiling is your device's memory.
How to use the bulk image converter
- Select your images — hold Shift or Ctrl to pick several.
- Choose the output format and quality.
- Process, then download the ZIP.
About this tool
Converting one image at a time is fine until you have forty of them. This takes a whole selection, converts each to the format you choose, and hands back a single ZIP.
Batch size is bounded by memory rather than by any rule of ours, and the limit is less obvious than it looks. A decoded image occupies width × height × 4 bytes in memory no matter how small the file is on disk — a 3 MB phone photo at 4032×3024 becomes about 49 MB once decoded. That is why a dozen holiday photos can exhaust a tab while looking modest in a folder.
So files are processed strictly one at a time, and each is released before the next is opened. Peak memory stays near a single image rather than the whole batch, which is what makes a hundred files workable. If a very large batch does stop, splitting it in half is the fix.
A file that fails is reported and skipped rather than stopping the run, so one corrupt image in a folder of ninety-nine good ones does not cost you the batch. The result table shows what happened to each file, including why anything failed.
Nothing is uploaded. The ZIP is assembled on your device too, so a batch of a hundred photos does not become a hundred uploads — which matters more for a batch than for a single file, since batches tend to be personal photo libraries or unreleased client work.
Common uses
- Converting a folder of PNGs to WebP for a website.
- Standardising mixed camera output on one format.
- Preparing a set of images for a system that accepts only JPG.
Frequently asked questions
- How many images can I convert at once?
- Up to 100 per batch. The real constraint is memory: images are decoded one at a time and released, so peak usage stays near one image rather than the whole batch.
- What happens if one file fails?
- It is reported in the table with the reason and skipped. The rest of the batch continues, and the ZIP contains everything that succeeded.
- Are my images uploaded?
- No. Every conversion and the ZIP itself happen on your device, which is the point of doing it in the browser rather than on a server.
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