Are my images uploaded to a server?

No. The entire conversion runs inside your browser using the HTML5 Canvas API. Your BMP file never leaves your device.

Why is the PNG so much smaller than the original BMP?

BMP stores raw uncompressed pixel data, which makes files very large. PNG uses lossless compression (DEFLATE) that can reduce file size by 50–90% for typical images while preserving every pixel perfectly.

Does the PNG preserve all the colors from the BMP?

Yes. The conversion is lossless — every pixel from the BMP is captured exactly and stored in the PNG without any quality loss.

Does the tool support 32-bit BMP files with transparency?

Yes. If the BMP contains an alpha channel (32-bit BGRA), the browser will decode it correctly and the resulting PNG will preserve that transparency.

Is there a file size limit?

The practical limit is your browser's available memory — typically several hundred megabytes. Very large BMP files may be slow to process on low-end devices.

What if the image looks wrong after conversion?

Some non-standard BMP variants (e.g., OS/2 BMPs or exotic color depths) may not decode correctly in all browsers. If you encounter issues, try opening the BMP in an image editor first and re-saving it as a standard 24-bit BMP.

BMP to PNG Converter

Upload a BMP file and download a lossless PNG — converted instantly in your browser with no file upload.

Upload BMP

Click or drag a BMP here

BMP files only — converted to lossless PNG in your browser

Preview (PNG output)

Upload a BMP to see the PNG preview

Conversion happens instantly, entirely in your browser

Downloaded!

Summary

This tool converts BMP (Bitmap) images to lossless PNG format entirely inside your browser using the HTML5 Canvas API. BMP files are uncompressed and often very large; PNG applies lossless compression that can dramatically reduce file size while preserving every pixel. No files are uploaded to any server — your images stay completely private on your device. The resulting PNG supports full 24-bit color and alpha transparency.

How it works

Select or drag a BMP image onto the upload area.
The browser decodes the BMP file using its built-in image decoder.
The Canvas API captures the decoded pixels and generates a lossless PNG.
A live preview and file size comparison appear immediately.
Click "Download PNG" to save the converted image to your device.

Use cases

Shrink large uncompressed BMP files from Windows Paint or legacy software.
Prepare BMP screenshots or diagrams for web use in PNG format.
Convert BMP icons or graphics for use in web design workflows.
Archive bitmap images in efficient lossless PNG format.
Share BMP images online where PNG is the expected or required format.
Convert BMP exports from CAD, medical imaging, or industrial tools to PNG.
Process images privately without uploading to any third-party service.
Reduce disk space by replacing bulky BMP files with compressed PNGs.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu