BMP to PNG Converter

Summary: How to Convert BMP to PNG Free and Privately

BMP to PNG conversion turns an uncompressed Windows bitmap into a PNG that holds exactly the same pixels, usually in a much smaller file. To convert here, click Select BMP Files (or drop .bmp files on the box). Each file converts at once, and you click Download PNG or Download All (ZIP). There is no signup, no watermark and no file limit.

The conversion is lossless. The tool reads the BMP itself instead of redrawing it on a canvas, so colors and semi-transparent pixels are copied exactly, and it then writes the PNG in a compact layout chosen from its colors: a palette of up to 256 colors, greyscale, 24-bit RGB or RGBA. It runs in your browser; nothing is uploaded (you can check the Network tab in DevTools).

Need the opposite for an old program that only reads bitmaps? Use the PNG to BMP converter. For a smaller photo and a little quality loss, turn the PNG into a JPG with the PNG to JPG converter or a WebP with the PNG to WebP converter.

Table of Use: Which BMPs Become Which PNGs

Why BMPs are big: an uncompressed BMP stores every pixel, so its size is set by the dimensions alone. Row size in bytes = ((bits per pixel × width + 31) ÷ 32, rounded down) × 4, and the pixel data = row size × height. A 24-bit 1,920 × 1,080 BMP therefore holds 5,760 × 1,080 = 6,220,800 bytes of pixels, whether the picture is a blank window or a detailed photo. PNG compresses that, and the tool chooses the layout like this:

Features

• Pixel-exact reading. Windows and OS/2 bitmaps at 1, 2, 4, 8, 16, 24 and 32 bits per pixel, RLE4 and RLE8 compression, custom bit masks, top-down files and alpha are decoded by the tool itself.
• Compact lossless PNG. The layout is picked per image from its colors; greyscale, RGB and RGBA rows each get the prediction filter that suits them, palette images are stored unfiltered, and DEFLATE runs at maximum compression.
• A report on every card. Original (BMP) and Converted (PNG) previews side by side, the pixel size, before and after file sizes, a "smaller" or "larger" percentage and a line such as 24-bit → PNG 8-bit palette, 37 colours. A total appears above the cards.
• Batch with one ZIP. Convert any number of files, and Download All (ZIP) saves converted-png.zip. Duplicate names get -2, -3 and so on.
• Names kept. photo.bmp becomes photo.png; .dib files work too.
• Honest errors. A file without the BM signature is skipped with a message, and a truncated or damaged BMP reports an error instead of producing a broken PNG. Images above 268,435,456 pixels are refused.
• Not carried over. DPI and embedded color profiles are not written to the PNG; only the pixels are. Set DPI in your layout program if you need it for print.

How to Use the BMP to PNG Converter

1. Click Select BMP Files, or drop .bmp (or .dib) files on the dashed box. In a file picker, Ctrl+A (⌘+A) selects every file in the open folder.
2. Wait a moment while each card shows Converting…, then check Original (BMP) against Converted (PNG) and the size line.
3. Click Download PNG on a card to save that file.
4. For many files, click Add More to add others and Download All (ZIP) to save them together. The trash icon on a card removes it, and Clear All empties the page.

After converting, you can resize the pictures with the image resizer or shrink them further with the image compressor. Other old formats have their own converters too: the JPG to PNG, GIF to PNG, TIFF to PNG and ICO to PNG converters all work the same way.

Who Can Use It

• Office and home users who need to email or upload a bitmap that is too big or not accepted.
• Developers and engineers handling output from older Windows software, scanners, industrial cameras and embedded displays, which still write BMP.
• Designers and game modders who want a lossless copy of a sprite or texture with its transparency kept.
• Students and teachers converting lab screenshots into files that open everywhere.

FAQs