Turn bulky Windows bitmap files into lossless PNGs: identical pixels, a fraction of the file size, and support in every browser and app.
No limits or paywall.
Use instantly, no account.
Processed inside your browser.
Clean, full-quality output.
No upload queue or waiting.
Works on phone and desktop.
BMP is one of the oldest image formats still in circulation, and its biggest problem is size. Most bitmaps store every pixel raw, with no compression at all, so a single full-HD screenshot weighs around 6 MB and a folder of scans can fill a drive. They are also awkward to share: many websites, email clients and apps either refuse BMP or handle it inconsistently.
Converting to PNG fixes both problems without any compromise. PNG is lossless, so every pixel stays exactly the same, but its compression typically makes files many times smaller. This free converter does it in your browser, for one file or a whole batch, with no upload and no watermark.
Before
BMP, 24-bit, 1920 × 1080 screenshot
≈ 6.2 MB
Uncompressed: every pixel stored raw, three bytes each.
After
PNG, lossless
≈ 0.3–1.5 MB
Exactly the same pixels, compressed without any loss.
Screenshots and graphics with flat colours shrink the most (often 90% or more). Photographs shrink less because their detail compresses less well, but PNG is still smaller than an uncompressed BMP.
Drop one or more .bmp images into the workspace at the top of the page, or click to browse.
PNG is preselected. No quality setting is needed because PNG is lossless.
Click Convert Now. Your browser re-encodes each bitmap as PNG.
Download PNGs individually or the whole batch as a ZIP archive.
| Property | BMP | PNG | Practical effect |
|---|---|---|---|
| Compression | Usually none | Lossless (DEFLATE) | Same pixels, smaller file |
| 1080p screenshot | ≈ 6 MB | ≈ 0.3–1 MB | Easy to email and upload |
| 1080p photo | ≈ 6 MB | ≈ 2–4 MB | Still smaller, still lossless |
| Web browser support | Limited / inconsistent | Universal | PNG works on any website |
| Transparency | Rarely used | Full alpha channel | PNG handles logos and cut-outs |
| Metadata and colour profile | Basic | Supported | PNG fits modern workflows |
A Windows bitmap is essentially a header followed by a grid of pixel values. In the common 24-bit form, each pixel takes three bytes (blue, green and red), rows are padded to a multiple of four bytes and, in most files, nothing is compressed. That makes BMP simple to read and write, which is why old software and equipment used it, but it also makes the file size depend only on the dimensions: a 1920 × 1080 bitmap is about 6.2 MB whether it shows a busy photo or a blank white page.
PNG takes the same pixels and compresses them losslessly. It first applies a per-row filter that predicts each pixel from its neighbours, then compresses the result with DEFLATE. On images with repeated colours and smooth areas, predictions are almost perfect, which is why screenshots and diagrams shrink dramatically.
Because neither format discards information, converting BMP to PNG is a pure change of container. If you compared the two files pixel by pixel, they would match exactly. That makes PNG ideal for archiving scans, preserving screenshots used as evidence or documentation, and keeping graphics crisp.
This is different from converting to JPG, which throws away detail to reach a much smaller size. For photographs that you only want to share, JPG may still be the better choice, and the BMP to JPG converter handles that.
Savings depend on content. Flat graphics, interfaces and text-heavy screenshots often shrink by 90% or more, so a 6 MB bitmap becomes a few hundred kilobytes. Photographs and noisy scans shrink less, typically by a third to a half, because random detail is hard to compress without loss.
Across an archive of hundreds of bitmaps, the difference adds up to gigabytes. The files also become far easier to email, upload and back up.
Although browsers can usually display BMP, support across web platforms, content management systems, messaging apps and online forms is uneven, and many explicitly accept only JPG and PNG. PNG is supported everywhere, including every browser, office suite and design tool, and it adds modern features BMP rarely uses, such as transparency and colour profiles.
Bitmaps often come from scanners and business software, so they may contain sensitive documents. This converter reads each file, decodes it on a canvas and writes the PNG on your device. Nothing is uploaded or stored, and there is no limit on how many files you convert.
Bitmaps often live in large folders of scans or exports collected over years. Converting them in one go saves the most space, but archives deserve a careful workflow so nothing is lost:
Shrink folders of scanned documents and photos without losing a single pixel.
Convert screenshots and exports from older Windows programs or equipment into a format every app reads.
Turn bitmap screenshots into compact PNGs for manuals, tickets and wikis.
Forms and CMS tools that reject BMP accept PNG without issue.
No. Both formats are lossless, so the PNG contains exactly the same pixel values as the BMP. Only the way the data is stored changes.
It depends on content. Screenshots, diagrams and graphics with flat colours often shrink by 90% or more. Photos shrink less, typically by a third to a half, because noise and fine detail compress less well.
Most BMP files are uncompressed: a 24-bit bitmap stores three bytes for every pixel, so a 1920 × 1080 image is about 6 MB no matter what it shows. PNG compresses that data losslessly.
No. Conversion runs inside your browser, so your images never leave your device.
Yes. Add as many as you like, convert them in one pass, and download a single ZIP file.
Choose PNG to keep every pixel identical, which is best for screenshots, diagrams, icons and archives. Choose JPG for photos when a much smaller file matters more than perfect fidelity; see the BMP to JPG converter.
BMP is an old Windows format. You meet it in scans from older scanners, screenshots from legacy software, exports from industrial or medical equipment, and old archives.
Yes. PNG is supported by every browser. For large photographs on a website, consider converting the PNG to WebP afterwards for an even smaller file with the PNG to WebP converter.
Yes. Paint, Photos, Word, PowerPoint and practically every Windows program open PNG files, just as they open BMP.
Most BMP files have no transparency. If a 32-bit bitmap does include an alpha channel and your browser decodes it, PNG keeps it; check the preview to be sure.
There is no fixed limit. Very large bitmaps use a lot of memory while converting, so huge scans are best converted on a desktop computer.