Convert BMP to WebP. Shrink bitmaps without uploading them
BMP stores pixels with little or no compression, a legacy of early Windows that can make a modest scan or Paint export occupy tens of megabytes. WebP typically reduces the same image by more than 90% while retaining good visual quality. Your browser decodes the BMP and uses Google’s WebAssembly codec to create the WebP locally. Old scans, screenshots, and equipment exports never leave your machine.
How it works
- Drop .bmp files below. Even very large ones are fine.
- Choose the WebP quality; 75–85 works well for scans and photos.
- Download each .webp and compare the size difference.
Frequently asked questions
Why are BMP files so large?
Most BMPs store every pixel uncompressed, so file size depends on dimensions rather than content. A 4000×3000 bitmap is roughly 36 MB no matter what it shows. WebP compresses intelligently, which is why the same image can drop to a fraction of a megabyte.
Will I lose quality?
WebP at the quality you choose is lossy, so technically yes, but at 80+ the difference is invisible for photos and scans. If you need a pixel-exact copy, convert BMP to PNG instead, which is lossless.
Can I convert a whole folder of BMPs at once?
Yes. Batch conversion is supported, and since processing is local the only limit is your device’s memory. Each finished WebP downloads as it completes.
Are my bitmaps uploaded?
No. The WebAssembly conversion runs in your browser, so BMP scans and other images stay on your device from start to finish.