Does converting BMP to PNG reduce quality?

No. Both BMP and PNG are lossless formats, so the conversion never degrades the image. The PNG output is pixel-identical to the source BMP, which is why there is no quality setting to adjust.

How much smaller will my PNG be than the BMP?

PNG's DEFLATE compression typically shrinks an uncompressed BMP by 50-80%, so a 10 MB BMP often becomes a 3-5 MB PNG with no visual change. The exact saving depends on content: flat-color images, screenshots, and diagrams compress the most, while photographic images compress the least.

Why is my BMP file so large compared to a PNG?

BMP stores raw uncompressed pixel data, with every pixel taking a fixed number of bytes regardless of the image content. PNG applies zlib/DEFLATE compression that collapses repeated pixel patterns, so the same picture takes a fraction of the space.

Can I convert BMP to PNG without uploading the file anywhere?

Yes. The conversion runs entirely in your browser through Rust compiled to WebAssembly, so the file is read and processed locally and never sent to a server. You can verify there are no file uploads in the DevTools Network tab.

Can I convert multiple BMP files to PNG at once?

Yes. Drop as many BMP files as you like and they are all converted in one batch on your device. A single file downloads directly, and multiple files download together as a ZIP, with no count cap.

Will BMP to PNG add or keep transparency?

It keeps whatever the source has but cannot add transparency that was not there. PNG supports full 8-bit alpha, but standard 24-bit BMP has no alpha channel, so a BMP with a solid background produces a PNG with that same solid background.

Is BMP or PNG better for the web?

PNG, by a wide margin. It is accepted everywhere by browsers, web forms, chat apps, and design tools, whereas BMP is frequently rejected or displays poorly outside Windows, which is the practical reason most people convert in the first place.

Do I need to install software to convert BMP to PNG?

No. The converter runs in any modern browser with no install, no extension, and no account. Because it uses WebAssembly, it also continues to work offline after the page has loaded once.

BMP to PNG Converter (No Upload, Local)

BMP to PNG conversion takes your large, uncompressed Windows bitmap files and produces compact, universally accepted PNGs entirely in your browser, with no upload to any server. Most people land here because a .bmp (an old app export, a legacy screenshot, a scanned diagram, or a game sprite) is either far too big to email or simply rejected by a web form that only accepts PNG. Both formats are lossless, so the conversion fixes the size and compatibility problem without touching a single pixel of quality.

What this conversion actually does (and does NOT do)

BMP and PNG are both lossless raster formats, which means BMP to PNG conversion never degrades image quality. The output is pixel-identical to the source, so there is no quality slider to worry about and nothing to lose. The real benefit is size. A BMP stores raw uncompressed pixel data (every pixel occupies a fixed number of bytes regardless of content), which is exactly why BMP files are so large. PNG applies DEFLATE/zlib compression that exploits repeated pixel patterns, so a 10 MB BMP commonly becomes a 3-5 MB PNG, a 50-80% reduction, with no visible change at all.

How much you save depends entirely on the image content. Flat-color graphics, screenshots, UI captures, and line-art diagrams compress the most because they contain large runs of identical pixels. Photographic content compresses the least because adjacent pixels rarely repeat. PNG also supports several color depths (indexed/palette, grayscale, 24-bit truecolor, and 32-bit with alpha), and converting a low-color BMP into an indexed/palette PNG can shrink it dramatically beyond what DEFLATE alone achieves.

The counterintuitive part is transparency. PNG supports full 8-bit alpha (variable per-pixel opacity), but standard 24-bit BMP carries no transparency at all, and only the rarely used 32-bit BMP variant holds an alpha channel. Converting BMP to PNG cannot invent transparency that was never in the source. If your BMP has a solid white or colored background, your PNG will have that same solid background. To make a region transparent you must edit the image separately; the format change alone will not do it.

When to choose BMP to PNG vs the alternative

Choose PNG when you need lossless quality plus a small file and the option of transparency, which covers logos, screenshots, UI mockups, and line art. Choose JPG (also written jpeg) instead only when the source is a photograph and some quality loss is acceptable in exchange for an even smaller file, since JPEG's lossy compression beats PNG on continuous-tone photos. If your BMP is a photo headed for the web, converting BMP to JPG will usually produce a smaller result, but for anything with sharp edges, text, or flat color, PNG is the right target.

How to convert

Drop one or many BMP files into the converter. They are read locally in your browser, never uploaded.
The output format is pre-selected to PNG. There is no quality slider here because PNG is lossless, so the result is always pixel-identical to the source.
If a BMP has no alpha channel (standard 24-bit BMP), the PNG keeps the existing solid background; transparency is not added.
Click Convert. A single file downloads directly as a .png, and multiple files download together as a ZIP with no count cap.

No upload. It runs on your device.

The conversion runs in your browser tab using Rust compiled to WebAssembly, so the image bytes are processed in memory on your own machine. There are zero network requests for the file itself, the tool works offline once the page has loaded, and there is nothing to delete afterward because nothing was ever uploaded. You can confirm this yourself by opening your browser's DevTools Network tab and watching it stay silent while you convert. This matters because BMP files are often legacy scans, internal diagrams, or proprietary game and sprite assets that should never be handed to a third-party server.

No limits

Convert as many BMP files as you want in a single batch. There is no file-size cap, no file-count limit, no watermark on the output, no sign-up, and no ads.

Frequently asked questions

Does converting BMP to PNG reduce quality?: No. Both BMP and PNG are lossless formats, so the conversion never degrades the image. The PNG output is pixel-identical to the source BMP, which is why there is no quality setting to adjust.
How much smaller will my PNG be than the BMP?: PNG's DEFLATE compression typically shrinks an uncompressed BMP by 50-80%, so a 10 MB BMP often becomes a 3-5 MB PNG with no visual change. The exact saving depends on content: flat-color images, screenshots, and diagrams compress the most, while photographic images compress the least.
Why is my BMP file so large compared to a PNG?: BMP stores raw uncompressed pixel data, with every pixel taking a fixed number of bytes regardless of the image content. PNG applies zlib/DEFLATE compression that collapses repeated pixel patterns, so the same picture takes a fraction of the space.
Can I convert BMP to PNG without uploading the file anywhere?: Yes. The conversion runs entirely in your browser through Rust compiled to WebAssembly, so the file is read and processed locally and never sent to a server. You can verify there are no file uploads in the DevTools Network tab.
Can I convert multiple BMP files to PNG at once?: Yes. Drop as many BMP files as you like and they are all converted in one batch on your device. A single file downloads directly, and multiple files download together as a ZIP, with no count cap.
Will BMP to PNG add or keep transparency?: It keeps whatever the source has but cannot add transparency that was not there. PNG supports full 8-bit alpha, but standard 24-bit BMP has no alpha channel, so a BMP with a solid background produces a PNG with that same solid background.
Is BMP or PNG better for the web?: PNG, by a wide margin. It is accepted everywhere by browsers, web forms, chat apps, and design tools, whereas BMP is frequently rejected or displays poorly outside Windows, which is the practical reason most people convert in the first place.
Do I need to install software to convert BMP to PNG?: No. The converter runs in any modern browser with no install, no extension, and no account. Because it uses WebAssembly, it also continues to work offline after the page has loaded once.

Need to go the other way or pick a different target? See the PNG to BMP converter, browse all image tools, or read why everything runs locally with Rust and WebAssembly.