Convert BMP to PNG — lossless shrink for legacy bitmaps
Drop a BMP below and get a PNG that is typically 50 to 70 percent smaller, pixel-perfect identical to the source. Runs entirely in your browser.
Your file is processed entirely in your browser. Nothing is uploaded.
The BMP format stores images as raw, mostly uncompressed pixel data. A 24-bit BMP dedicates 3 bytes per pixel and a 32-bit BMP with alpha uses 4 bytes per pixel, with no clever compression to reduce file size. This was fine in the 1990s when drives held files rather than photo libraries, but in 2026 it means a 1920x1080 BMP weighs 6 to 8 MB for content that a modern format can store in 1 to 2 MB with zero quality loss. PNG is the natural lossless upgrade: it keeps every pixel exactly, adds a full alpha channel, and applies modern lossless compression (DEFLATE with filters) that typically shrinks the file by 50 to 70 percent compared to the equivalent BMP.
This converter reads your BMP through the HTML5 Canvas API — supported natively in all modern browsers — and re-encodes the pixel data as a PNG. No quality is lost because both formats are lossless. The output file is a pixel-perfect copy of the input, just smaller. The entire process runs in your browser: no upload, no server, no stored copy of your file. If you can tolerate lossy compression and want an even smaller file, convert to JPG instead — a BMP to JPG conversion can typically shrink by 95 percent or more.
How to convert BMP to PNG in 4 steps
- 1
Select your BMP file
Drop it in the dropzone or click to browse. BMPs of all common color depths are accepted — 1-bit, 4-bit, 8-bit, 24-bit, 32-bit.
- 2
Let the browser re-encode
Canvas reads the raw BMP pixels and produces a lossless PNG. Even huge BMPs finish in a second or two on a modern device.
- 3
Check the size difference
The result panel shows the original BMP size and the new PNG size. The savings depend on the content, but expect 50 percent or more on typical images.
- 4
Download the PNG
Save the PNG to your device. The image is pixel-identical to the BMP source, and you can delete the original BMP if disk space is tight.
BMP vs PNG: why PNG wins on every metric except compatibility
BMP and PNG both carry full lossless pixel data, so the visual content is identical between the two. Everything else is a PNG advantage. PNG uses the DEFLATE algorithm with pre-filter passes to compress the pixel data losslessly, typically shrinking files by 50 to 70 percent relative to the same image in BMP. PNG supports a full 8-bit alpha channel for smooth transparency, while BMP alpha is awkward and inconsistently supported across tools. PNG has better metadata, better color profile handling, and is the de-facto standard for lossless images on the modern web, while BMP is essentially a legacy Windows format with very little active tooling support outside Microsoft products. For any workflow that does not specifically require BMP, PNG is strictly the better choice.
When should you convert BMP to PNG?
Shrinking a BMP archive without losing quality
If the original quality matters (a scanned document, a carefully-retouched photo, a high-value asset), PNG is the right target: same pixels, much smaller file.
Importing into modern web tools
Most modern CMS platforms, design tools, and photo managers handle PNG gracefully and BMP awkwardly. PNG just fits the modern toolchain better.
Preserving alpha transparency
If your BMP uses 32-bit mode with alpha, PNG gives you a proper alpha channel that every modern tool understands. BMP alpha is often interpreted inconsistently.
Preparing legacy screenshots for documentation
Old Windows-era BMPs from software documentation can be modernized to PNG for easy embedding in new docs, wikis, or knowledge-base articles.
Frequently asked questions
- Is the PNG pixel-identical to the BMP?
- Yes. Both formats are lossless, so the conversion preserves every pixel exactly. Reading the PNG back and comparing it to the BMP at the pixel level gives a perfect match.
- How much smaller will the PNG be?
- It depends on the content. Photographs typically shrink 30 to 60 percent, flat-color graphics can shrink 80 percent or more. The exact ratio depends on how predictable the pixel pattern is, which is what PNG’s compression exploits.
- Does the PNG preserve transparency from the BMP?
- Yes, as long as the BMP is in 32-bit mode with a real alpha channel. The alpha values are transferred unchanged to the PNG output.
- Should I use JPG instead for even smaller files?
- Only if you are willing to lose some quality. JPG uses lossy compression and can produce files 95 percent smaller than BMP, but with visible artifacts on text and sharp edges. Use PNG when quality matters, JPG when size matters more.
- Does my BMP leave my device?
- No. The conversion runs entirely through the HTML5 Canvas API in your browser. Your BMP is decoded locally, re-encoded locally as PNG, and handed to you as a blob download. FileShrink has no server that handles your files.