BMP to PNG Converter
Convert BMP (Windows Bitmap, 1990) to PNG (Portable Network Graphics, 1996) entirely in your browser. Output files are dramatically smaller — typically around 80% the size for ordinary photographs. Files never leave the tab — there is no upload.
Which formats are supported?
Inputs: PNG, JPEG, WEBP, AVIF, GIF, BMP, ICO, TIFF (Safari) and HEIC/HEIF (via libheif WASM, loaded on demand). Outputs: PNG, JPEG, WEBP, AVIF — each with an optional WASM encoder variant in the dropdown (mozjpeg, oxipng, libwebp, libavif) for tighter compression or consistent output across browsers. Vendor camera RAW formats (CR2/CR3/NEF/ARW/DNG/...), PSD, EPS, TGA, XCF and ICNS are still rejected — those need format-specific decoders we haven't shipped yet.
Both BMP and PNG are lossless formats — no pixel changes between input and output. The size difference comes from the compression algorithm, not from throwing away detail. Round-tripping BMP → PNG → BMP reproduces the original bytes once you account for re-filtering.
Both formats support a true alpha channel — anti-aliased logos, drop shadows and translucent overlays survive the round-trip unchanged.
PNG is the natural choice for Logos, icons, UI screenshots, text, Anything with sharp edges or flat colour, and Images that need a true alpha channel. It is a poor fit for Photographs (will be much larger than JPG/WEBP/AVIF) and Animated content. Every browser since IE 7; every modern OS.
BMP: what it is
BMP usually stores raw uncompressed pixel data plus a header. A 1920×1080 photo is roughly 6 MB as BMP vs 200–500 KB as JPEG.
Still common as the export format from legacy Windows scanners, GIS software and some embedded device imagers.
PNG: what it is
PNG uses DEFLATE (the gzip algorithm) over filtered scanlines. It is lossless: a PNG round-trip never changes a pixel.
Encoding cost lives almost entirely in choosing per-row filters. The oxipng encoder we ship trials more filter combinations than canvas does and typically shrinks files 10–25% further.
At a glance
- Typical size change
- ~80% smaller
- Transparency preserved
- Yes — both formats support alpha channels
- Compression
- BMP (lossless) → PNG ( lossless)
- PNG browser support
- Every browser since IE 7; every modern OS.
Frequently asked questions
Is the converted PNG smaller than the original BMP?
On a typical photograph, dramatically smaller — typically around 80% the size. Synthetic graphics (logos, screenshots) may behave very differently — try a single file first if size matters.
Will my BMP be uploaded to convert it?
No. The conversion runs inside the browser tab using WebAssembly. Your file is never sent over the network — drop it, convert it, download it, all on your machine.