Convert BMP to PNG
100% private — runs on your device, never uploaded. Works offline once loaded.
Convert old BMP bitmap images into compact, widely-supported PNG files. Everything runs locally in your browser — no uploads.
The BMP format, briefly
BMP (bitmap image file) is one of the oldest image formats still in circulation, originally built into Windows in the late 1980s. In its most common form it stores every pixel's colour value with no compression at all, which is exactly why BMP files are so large — a simple 4000×3000 photo can weigh 30–40MB as an uncompressed BMP, compared to a few megabytes as a compressed format.
That lack of compression made BMP simple and fast to read decades ago, but it's a poor fit for anything you want to store, email, or publish today.
Where BMP files still turn up
BMP is still the default output of a surprising number of legacy tools: Windows Paint's older save presets, certain document scanners, medical and industrial imaging equipment, screen-capture utilities on older Windows builds, and CAD or engineering software that exports raw bitmap data. If you've inherited a folder of images from an old backup, a scanner, or a piece of specialised hardware, there's a decent chance some of them are BMP.
- Scanned documents or forms saved directly by scanner software
- Screenshots taken with legacy Windows capture tools
- Exports from CAD, GIS, or scientific instrumentation software
Why PNG is the natural replacement
PNG uses DEFLATE compression, which is lossless like BMP — no pixel data is discarded — but typically shrinks the file to a fraction of the original size, especially for images with flat colour areas like scanned text, logos, or diagrams. PNG also adds transparency support that BMP lacks, and it's readable by essentially every browser, phone, and editing tool made in the last twenty years, unlike some newer formats.
Practical tip
If you're converting scanned documents, expect the biggest size reduction on pages that are mostly white background and black text — PNG's compression handles large flat colour regions extremely efficiently, often shrinking files by 80–95% with zero loss in readability.
Why people convert BMPs immediately
A BMP is often fine as a temporary capture format, but it is awkward for almost everything that comes next. Emailing it is slow, cloud drives sync it more heavily than necessary, and many web forms reject huge bitmap files outright even when the visible picture is simple. PNG solves that without changing the pixels you care about. For scanned forms, diagrams, screenshots, and line art, the savings can be dramatic while the image stays identical to the source, which is why BMP is usually the starting point and PNG is the format you actually keep.
Frequently asked questions
Why convert BMP to PNG?
BMP files are uncompressed and very large. PNG is lossless too but far smaller and supported everywhere.
Are my images uploaded?
No — everything runs in your browser and your files stay private.
Why are BMP files so much bigger than other formats?
Standard BMP stores pixel data with little or no compression, so file sizes scale directly with resolution and colour depth rather than with actual image complexity.
Will I lose any quality converting BMP to PNG?
No, both formats are lossless, so the PNG is pixel-for-pixel identical to the source BMP — you only gain a smaller file size.
Does this work with indexed-colour or grayscale BMP files?
Yes, BMP variants including 24-bit, 8-bit indexed, and grayscale bitmaps are all decoded and re-encoded correctly as PNG.
Can I convert several BMP files at the same time?
Yes, add multiple BMP files at once and download all the converted PNGs together as a ZIP.
Will old Windows icons or cursors saved as BMP convert correctly?
Standard BMP image files convert fine; note that .ICO and .CUR files are a different container format and aren't handled by this tool.
Is there any downside to converting?
None for image quality — the only reason to keep the original BMP would be if a specific legacy application requires that exact file format as input.
Why does PNG usually shrink scanned BMP documents so much?
Scanned paperwork often contains huge areas of repeating white background and dark text, which PNG compresses extremely efficiently. Uncompressed BMP stores all of that repetition literally, so the file balloons unnecessarily.
Should I delete the original BMP after converting?
If you have confirmed the PNG opens correctly and your workflow does not require BMP, keeping only the PNG is usually fine. The image content is preserved, so the BMP is rarely needed afterward.
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