BMP to PNG

How it works

BMP is Windows' native bitmap format, and most BMP files store every pixel completely uncompressed. PNG applies real lossless compression on top of the same pixel-perfect accuracy, and it's what most web tools and design software expect instead. This tool converts BMP images to PNG directly inside your browser tab — no server, no upload, no waiting in a queue.

When you drop a file, Moyang reads its first bytes to confirm it's really a BMP, then hands the bytes to a background Web Worker. If the source carries an alpha channel — some newer BMP variants do — it's preserved in the PNG output. Your original file is never modified, and nothing ever leaves your device.

Because everything runs locally, there's no 10-conversions-a-day limit, no 100MB cap, and no processing queue — the kind of restrictions server-based converters impose to control their hosting bill. Convert one file or fifty; once a batch is done, download every result at once as a single ZIP.

Limitations

Images over 100 megapixels aren't converted — decoding runs entirely in your browser's memory, and a file that large risks crashing the tab before it even gets to PNG encoding. Otherwise this is a clean, fully lossless conversion: no pixel data is discarded, only redundancy is compressed away.

FAQ

Is this BMP to PNG converter really free?

Yes — completely free, with no file size limits, no daily quota, and no account required. All conversion happens in your browser, so there's no server cost to recoup.

Why convert BMP to PNG if both are lossless?

BMP is almost always stored completely uncompressed, while PNG applies real lossless compression — so a PNG of the same image is typically much smaller with zero quality difference. PNG is also what most web tools and design software expect instead of BMP.

Where do BMP files even come from?

BMP is Windows' native bitmap format — screenshots, some scanner and Windows Paint exports, and older Windows software still produce it by default. PNG is the more portable, more widely accepted equivalent.

Is transparency preserved?

If the source BMP carries an alpha channel (some newer BMP variants do), it's preserved in the PNG output. Most BMP files have no transparency at all, in which case the PNG is simply fully opaque, same as the source.