Convert BMP to AVIF

No — that is the whole reason I built this. The conversion runs in your browser using WebAssembly, so your files never leave your device; there is no server in the loop at all. It also means the tool keeps working offline once the page has loaded, and there is no file size limit beyond your device’s memory.

The biggest on this site. A 6 MB uncompressed screenshot typically lands between 30 and 120 KB as AVIF — a 98–99% reduction. Nothing magical is happening: BMP simply never compressed the data, and AVIF compresses it about as hard as currently possible.

For sharing and publishing, yes. For the archive itself, I would say no: AVIF discards information permanently, and scans of irreplaceable documents deserve a lossless format. Convert the archive to PNG (still 50–90% smaller than BMP), then make AVIF copies for anything you publish.

Almost certainly not — the kind of legacy tools that output BMP predate AVIF by decades. Think of this as a one-way trip toward the web: browsers all render AVIF, old desktop software mostly does not. If you need something old programs can open, BMP to PNG or BMP to JPG is the better tool.

By destination. Publishing on the web → AVIF, the 98–99% cut speaks for itself. Feeding software that predates 2020 → BMP to PNG, lossless and universally readable. Unsure → WebP splits the difference. The one wrong answer is leaving screenshots as multi-megabyte BMPs on a web server.

Refuse, no — but for one-of-a-kind scans (family photos, signed documents, original art) convert to a lossless format first and treat AVIF strictly as the sharing copy. AVIF discards data permanently, and a 1-bit fax-style scan can come out slightly softened. Masters stay lossless; only the copies get compressed.