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BMP to PNG Converter

Data & Digital

Convert BMP bitmap images to PNG free online. Drag, drop, and download instantly — the conversion runs entirely in your browser, so nothing is uploaded.

Reviewed by the thecalcu.com team · Last updated July 16, 2026

Drag & drop a BMP file here

or click to browse — max 15.00 MB, stays on your device

What is a BMP to PNG?

A BMP to PNG Converter takes a bitmap image, one of the oldest image formats, built into Windows and typically stored with little or no compression, and re-encodes it as a compact, lossless PNG. BMP files are simple to decode but often needlessly large, since they usually store every pixel at full size without the compression that formats like PNG apply. Converting to PNG keeps the exact same image quality while shrinking the file considerably.

This tool performs the conversion entirely in your browser using the Canvas API: it decodes the BMP and re-encodes the pixel data as PNG, no upload, no server round-trip. It pairs naturally with the PNG to BMP Converter for the reverse direction, and with the JPG to PNG Converter if you're standardizing older image formats into PNG.

Why Use a BMP to PNG Converter?

Old scanners, legacy Windows applications, and some screenshot tools still default to BMP, producing files far larger than necessary for modern storage or sharing. Converting to PNG on demand modernizes these files for use in current image editors, web uploads, and document tools without any loss of visual quality.

Two concrete situations this solves: shrinking a scanned document or old screenshot saved as BMP into a much smaller PNG for archiving or sharing, and converting a BMP asset from legacy software into PNG for use in a modern design or development workflow.

Who Should Use This Converter?

  • Anyone digitizing old scans or documents saved as uncompressed BMP who wants a smaller, more shareable file.
  • Developers modernizing image assets from legacy Windows software into PNG for current build pipelines.
  • IT and support staff converting BMP screenshots from older systems into PNG before attaching them to tickets or documentation.
  • Designers working with BMP exports from specialized or legacy tools who need a broadly compatible format.
  • Users going the other direction should see the PNG to BMP Converter for producing an uncompressed BMP from a PNG.

What Insights Does the BMP to PNG Converter Give You?

Once converted, the tool shows your Original (BMP) and Converted (PNG) side by side, along with the file size of each, typically the clearest demonstration of just how much smaller PNG's compression makes the same image compared to BMP's uncompressed storage.

Because the conversion is lossless in both directions, the pixel dimensions shown for the converted PNG always match the source BMP exactly, only the file size and internal encoding change.

How to use this BMP to PNG calculator

  1. Drag and drop a .bmp file onto the upload area, or click it to browse your device.
  2. Review the file preview showing the image's dimensions and file size.
  3. Click Convert to PNG.
  4. Compare the Original (BMP) and Converted (PNG) previews and file sizes side by side.
  5. Click Download PNG to save the file, or Copy PNG to copy it directly to your clipboard.
  6. Click Change to start over with a different file.

Formula & Methodology

The browser decodes the BMP's pixel array, typically stored uncompressed, row by row, bottom-up, into a raw RGBA bitmap, draws that bitmap onto an HTML canvas, then calls the canvas's PNG export (canvas.toBlob(..., "image/png")) to compress it losslessly using PNG's DEFLATE-based algorithm.

For example, a 1024×768px uncompressed 24-bit BMP file is roughly 2.36MB by construction (1024 × 768 × 3 bytes per pixel, plus row padding), while the equivalent PNG typically lands between 200KB and 800KB depending on image content, a reduction of roughly 3–10x with zero quality loss.

Frequently Asked Questions

It decodes a BMP bitmap image, an uncompressed or lightly compressed format built into Windows, using your browser's native decoder, draws it onto an HTML canvas, and re-encodes the pixel data as a compressed, lossless PNG file. The visual result is identical; only the file's internal storage format changes.
The entire conversion runs in your browser using the Canvas API, and the file never leaves your device. This makes the tool safe for images you'd rather not send to a third-party server.
BMP files are typically uncompressed, which makes them far larger than necessary for storage or sharing, while PNG compresses the same pixel data losslessly to a fraction of the size. Converting to PNG shrinks the file without losing any image quality.
Both BMP (in its common uncompressed form) and PNG can represent an image with full fidelity, so converting between them doesn't discard any pixel data. The PNG will look pixel-for-pixel identical to the BMP, just stored far more efficiently.
Often dramatically smaller, an uncompressed BMP stores every pixel at full size with no compression, so a PNG of the same image is commonly 50–90% smaller, depending on how much repetition and flat color the image contains. Photos and screenshots typically see the largest reductions.
Drag and drop your .bmp file onto the upload area, or click it to browse your device, then click Convert to PNG. The converted PNG appears next to your original file within moments, ready to download or copy.
BMP is one of the oldest image formats built directly into Windows, so many legacy applications, scanners, and screenshot tools default to it since it requires no compression logic to write. Converting these files to PNG modernizes them for use in current software and web contexts.
You can upload a BMP up to 15MB, though because BMP is uncompressed, that limit corresponds to a smaller pixel count than an equivalent JPG or PNG of the same file size. Very large files may take a moment longer to decode and re-encode.
Yes, the Copy PNG button copies the converted image directly to your clipboard in supporting browsers, so you can paste it straight into another application. If your browser doesn't support clipboard image writes, use Download PNG instead.
Yes, BMP has been supported natively by all major browsers for a very long time, since it's a simple, uncompressed format with no complex decoding required. This makes BMP to PNG conversion reliable across virtually any modern browser.
Most BMP files don't include an alpha channel, since transparency support was added to the format later and is inconsistently used. If your BMP does include transparency, this tool preserves it in the PNG output; if not, the PNG will simply be fully opaque, matching the source.
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