Processed entirely on your device — nothing is uploaded
How to use the bmp to png converter
- 1Drop your BMP files onto the box above, or click to browse for them.
- 2Adjust the quality slider if you want a smaller file or a sharper result.
- 3Press Convert and wait while your browser re-encodes each image.
- 4Download the finished PNG files.
Why convert BMP to PNG?
An uncompressed Windows-native format that stores raw pixel data with essentially no compression at all. That is exactly what you want when the file is being archived or edited, and an obstacle when it has to be emailed, uploaded or served on a web page. PNG solves the second problem.
A lossless raster format built for screenshots, logos and any artwork with hard edges or transparency. For a BMP source specifically, the payoff is pixels survive the round trip untouched — no generation loss, ever — and alongside that, full 8-bit alpha channel, so transparency stays clean against any background and universally supported by every browser, OS, email client and CMS since the late 1990s.
The cost of the switch is worth stating plainly before you make it: file sizes are typically 3-10x larger than JPEG for photographs and there is no quality dial to trade size against fidelity. Weigh that against what BMP was giving you, which was trivially simple structure that old industrial and medical software can always read.
Where BMP files usually come from
Most people arrive at this page holding one of three things: output from scanner software or an industrial machine-vision camera, screenshots taken by a legacy Windows application, or frames dumped by scientific or medical imaging equipment.
Knowing which one you have matters, because it changes the right settings. Photographic content tolerates aggressive compression well — the eye is forgiving about noise in a sky or a skin tone. Screenshots, charts and line art do not: they contain hard edges and small text, which is precisely what lossy compression handles worst. If your BMP is the second kind, push the quality slider higher than feels necessary.
BMP originated in legacy Windows software, scanners and industrial equipment, and that lineage explains most of its behaviour: an uncompressed Windows-native format that stores raw pixel data with essentially no compression at all.
What happens to quality when you convert BMP to PNG
Both formats are lossless, so this conversion is mathematically exact: the pixels that come out are bit-identical to the pixels that went in. You are changing the container and the compression scheme, not the image.
That makes this one of the few conversions you can perform repeatedly without any degradation at all.
How much smaller (or larger) will the file be?
Expect a dramatic reduction. BMP stores raw pixels with no compression at all, so a 12-megapixel image occupies roughly 36 MB. The same picture as PNG typically lands between 1 and 4 MB — a reduction of 90% or more. This is the conversion with the largest size payoff of any on this site.
There is no quality dial to turn, because PNG is lossless — the size you get is the size the image compresses to. The one lever you do have is the max-width setting: halving the width quarters the pixel count, and file size falls roughly in step.
When converting BMP to PNG is the wrong move
This conversion is not always the right answer, and it is cheaper to know that now than after you have replaced your originals. Skip it if you need the smallest possible file and your audience is on modern browsers, in which case AVIF or WebP will beat PNG comfortably.
A reasonable default: keep your BMP originals in a folder you do not touch, and treat the PNG output as a derived, disposable copy for whatever you are publishing or sending. That way a bad quality setting costs you a re-export rather than the image.
Your BMP files never leave your device
Most online converters upload your file to a server, convert it there, and hand you back a download link. A copy of your image then sits on someone else's disk under a retention policy you did not read.
This converter does not work that way. Your BMP is decoded by the browser's own image pipeline, drawn into an off-screen canvas, and re-encoded as PNG — all inside this tab, on your processor. There is no upload progress bar because there is no upload, no queue because there is no server, and nothing to delete afterwards.
You can verify this yourself: open your browser's network panel and watch that nothing is sent, or simply disconnect from Wi-Fi after the page has loaded and convert anyway. A practical side effect is that speed depends on your own hardware rather than on someone else's server load, and there is no file size cap beyond your available memory.
Frequently asked questions
Is this BMP to PNG converter really free?
Yes — no account, no watermark, no daily cap. The conversion runs on your own processor, so it costs nothing to serve and there is nothing to meter.
Are my BMP files uploaded anywhere?
No. The file is read locally, decoded into a canvas and re-encoded to PNG entirely within this browser tab. No image data crosses the network at any point.
Can I convert several BMP files at once?
Yes. Drop in as many as you like and each is converted with the same settings, one at a time so a large batch does not exhaust your memory.
Why is my BMP so much bigger than everything else?
BMP stores raw pixel data with essentially no compression, so size scales directly with resolution. A 12-megapixel BMP is around 36 MB regardless of what the picture shows.
Does the converter change my image dimensions?
Not unless you ask. Output keeps the exact pixel dimensions of the source; the max-width box is empty by default and only resizes when you fill it in.