What is a BMP file?
BMP is the original Windows bitmap format. It stores pixels with little or no compression, so files are enormous — a single photo can be tens of megabytes. BMPs mostly appear today as exports from old software, scanners, medical devices, and industrial equipment.
In short, BMP is the uncompressed Windows legacy format. It is best for nothing modern — BMPs are almost always converted to another format before being shared or published. Its main limitations are huge file sizes, no transparency in common variants, no animation.
Why convert BMP to AVIF?
AVIF is built on the AV1 video codec and delivers the strongest compression of any mainstream image format — files are often about half the size of an equivalent JPG and noticeably smaller than WebP at the same visual quality. It supports transparency, HDR, and wide color gamuts.
Converting from BMP to AVIF makes sense when you need performance-critical websites where every kilobyte counts, and modern image pipelines that can serve fallbacks. AVIF is supported by all current versions of Chrome, Firefox, Safari, and Edge.
AVIF supports full transparency, so images you later edit can take advantage of an alpha channel — though a converted BMP starts out fully opaque.
AVIF uses lossy compression, so use the quality slider to balance file size against fidelity — 80–90% is visually indistinguishable from the original for most images.
How to convert BMP to AVIF
Drag and drop one or more BMP files into the box above (or click to browse). Adjust the quality slider if you want smaller files or higher fidelity, then press Convert. Each file is decoded and re-encoded as AVIF on your own device in a second or two, and you can download results individually or grab everything as a ZIP.
Unlike most online converters, FileLark never uploads your files to a server. The conversion runs entirely inside your browser using modern web technology, which means it works offline once the page has loaded, there are no file size queues or daily upload limits, and your images can never be stored, scanned, or leaked — they simply never leave your device.