Convert BMP Bitmaps to Compact PNG Images

Decodes your BMP with the browser's image pipeline and re-encodes it as lossless PNG, which is typically a fraction of the size with no loss of quality. Convert one file or a batch, all inside the tab.

About the BMP to PNG Converter

A BMP stores every pixel uncompressed, which is why a bitmap of a plain screenshot can run to several megabytes when the same image as a PNG is a few hundred kilobytes. PNG applies lossless compression, so the pixels that come out are identical to the ones that went in — the file is smaller because it is stored more cleverly, not because anything was discarded.

The tool accepts BMP files and produces PNG. There are no quality settings, and there should not be: PNG is lossless, so there is no quality dial to turn. You add one file or several, press convert, and get PNGs back with the same base names. When you convert more than one, they are bundled into a ZIP so you are not saving them individually.

Key Features

  • Lossless every time: PNG encoding reproduces the exact pixels of the bitmap, so converting loses nothing — the only change is the file size.
  • Large size reduction: An uncompressed bitmap usually shrinks dramatically as PNG, particularly for screenshots, diagrams and anything with flat areas of colour.
  • Batch conversion: Add a folder of bitmaps at once; each is converted and the set comes back as a single ZIP archive.
  • Transparency supported on output: PNG carries an alpha channel, so if a converted image is later composited, it can hold transparency the source BMP could not.
  • No settings to weigh up: Because the conversion is lossless there is nothing to configure — the result is determined, not chosen.
  • Runs in the browser: Decoding and PNG encoding both use the browser's own image handling, so no bitmap is uploaded to be converted.

How to Use the BMP to PNG Converter

  1. Add one or more .bmp files.
  2. Press Convert Now.
  3. Download the PNG, or the ZIP if you converted several at once.

How It Works

Decoding uses the browser's native image support, which reads standard BMP files without difficulty. Encoding goes through the canvas, which produces a standard PNG.

There is one edge worth knowing about. The canvas works in eight bits per channel, so a BMP saved in one of the deeper or more unusual variants — 16-bit, or with an embedded colour profile — is normalised to standard eight-bit colour on the way through. For screenshots, diagrams, scanned documents and ordinary photographs this is invisible. For colour-critical work where a wide-gamut profile must be preserved exactly, a canvas-based conversion is not the right tool.

Batch size is limited by memory rather than by a fixed cap. Because each bitmap is fully decoded before being re-encoded, a large set of high-resolution bitmaps holds a lot of pixel data at once, so a very large batch is better split in two.

When You Need It

An engineer working with an older industrial control system finds its screen-capture function only outputs BMP, and needs those captures in a maintenance log that everyone can open without them bloating the document to tens of megabytes. Converting to PNG keeps the log light and the images crisp. The screenshots show the internal configuration of a client's plant, so a conversion that stays on the maintenance laptop rather than passing through a web service respects the access agreement.

Someone digitising an archive of old clip art and interface assets saved as bitmaps wants them in a modern format for a design library. PNG halves or better the storage while keeping the images pixel-exact, and doing it locally means an afternoon's batch does not depend on an upload for every file.

FAQ

Frequently Asked Questions

Will I lose any quality converting BMP to PNG?
No. PNG is a lossless format, so the pixels in the output match the pixels in the bitmap exactly. The file is smaller purely because PNG compresses the data efficiently where BMP stores it raw. This is the rare conversion where smaller and identical are both true at once.
Why is my PNG so much smaller than the BMP?
Because the BMP was storing every pixel uncompressed while the PNG compresses them. Images with large areas of the same colour — screenshots, diagrams, logos — compress especially well, so a reduction of eighty percent or more is common. A busy photograph compresses less but still shrinks.
Can I convert several bitmaps at once?
Yes. Add as many as you like and each is converted, with the results delivered as a single ZIP when there is more than one. The realistic limit is your device's memory, since each bitmap is decoded in full during conversion, so an enormous batch of high-resolution files is better done in a couple of passes.
Does converting keep transparency?
A standard BMP has no transparency to keep, so the question rarely arises — but the PNG that comes out does support an alpha channel, which matters if you later edit or composite the image. The conversion itself neither adds nor removes transparency; it carries across what the source had.
Are my bitmaps uploaded to be converted?
No. The BMP is decoded by your browser and re-encoded as PNG through the canvas, both happening in this tab. Nothing is sent to a server, which is worth knowing if the images are screenshots of a private system or scans of documents you would not post publicly.
My BMP had a special colour profile. Did it survive?
Probably not exactly. The conversion works in standard eight-bit colour, so an embedded wide-gamut profile is normalised rather than preserved. This is invisible for everyday images but matters for colour-managed print work, where you would want a tool that carries the profile through untouched.
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