Convert BMP to ICO
Free, unlimited BMP to ICO conversion that runs entirely inside your browser. No upload, no sign-up, no watermark.
Convert your BMP files to ICO
or drop them here, or paste with Ctrl+V · files never leave your device
Settings
Nothing queued yet. Add as many files as you like — everything runs on your own device.
Nothing is uploaded
Conversion runs in your browser. Your files never touch a server, so there is no copy of them to leak.
No sign-up, no watermark
No account, no email, no daily limit, and nothing stamped across your image.
Batch and folders
Drop a hundred files at once and download the results as a single ZIP.
Works offline
Once this page has loaded you can disconnect entirely and it still works.
This converter turns BMP images into ICO files without uploading anything. The conversion runs inside this page using your own device's processor, so your photos never leave your computer — there is no server copy to worry about, no queue to wait in, and no limit on how many files you convert.
BMP is Microsoft’s raw, uncompressed bitmap format — every pixel stored literally, with no compression at all. Strong on Windows, weak everywhere else, and never used online. ICO, by contrast, universal for its one job: favicons and Windows icons.
Every website needs a favicon, and .ico remains the format with the widest browser support — including the older browsers that ignore the modern PNG favicon link. Dropping your logo here produces a multi-size .ico ready to sit at the root of your site.
How to convert BMP to ICO
- Add your BMP files. Drag them onto the box above, click to browse, or paste an image straight from your clipboard. You can add as many at once as you like.
- Adjust the settings if you need to. The defaults suit most images. ICO is lossless, so there is no quality setting to adjust.
- Download the ICO file. Each file gets its own download button as soon as it finishes, and you can pull the whole batch down as a single ZIP.
What changes when you convert BMP to ICO
Every format conversion involves trade-offs, and vague tools hide them. Here is exactly what happens to your image in this particular conversion.
- Icons are square and capped at 256x256. A non-square image is centred and padded with transparency rather than stretched, and we write 16, 32 and 48 pixel entries into one file so browsers and Windows each pick the sharpest.
What happens to the file size
Measured, not estimated: two 1200 x 800 pixels references — a photograph and a flat-colour graphic — put through this converter.
| Reference image | As BMP | As ICO | Change |
|---|---|---|---|
| Photograph | 2.75 MB | 6 KB | -100% |
| Graphic with text | 2.75 MB | 3 KB | -100% |
Yours will differ: size depends more on what is in the picture than on the formats involved.
About BMP (Windows Bitmap)
BMP is Microsoft’s raw, uncompressed bitmap format — every pixel stored literally, with no compression at all.
Where you probably got it: Legacy Windows applications, scanners, and industrial equipment.
Strengths
- Dead simple and completely lossless
- Read by even the most primitive Windows tooling and embedded devices
- No decoding overhead, which some industrial and medical systems require
Limitations
- Enormous files — often 10–20x larger than a PNG of the same image
- Poorly supported on the web; browsers can display it but nobody serves it
- No transparency in the widely supported 24-bit form, so transparent areas are filled with a solid colour
About ICO (Windows Icon)
ICO is the Windows icon container, and the traditional format for a website’s favicon.
Support: Universal for its one job: favicons and Windows icons.
Strengths
- Holds several sizes in one file so each context picks the sharpest
- The one favicon format every browser understands, including very old ones
- Supports transparency
Limitations
- Only useful for icons — sizes are capped at 256x256
- Not a general-purpose image format
- Awkward to create in most image editors
Is it safe to convert BMP online?
Here, yes — and you can check rather than trust. Open your browser’s developer tools, switch to the Network tab and convert a BMP file: no request carrying your image is made. Disconnect from the internet after this page has loaded and the converter still works, which would be impossible if a server were doing the conversion.
That is worth verifying wherever you convert, because most online converters do upload, and BMP files are so often personal photos and documents people would not hand to a stranger. Once a file is on somebody else’s server you are relying on a privacy policy rather than on anything you can observe. We wrote up how to tell a safe converter from a risky one in more detail.
Frequently asked questions
How do I convert BMP to ICO?
Drag your BMP file onto the box above, or click it to browse. The conversion starts immediately in your browser and the ICO download appears within a second or two for most images. You can drop in a whole folder of files at once and download them together as a ZIP.
Are my BMP files uploaded to a server?
No. The conversion happens locally in your browser, so your files are never transmitted anywhere — the tool even works with the network disconnected once the page has loaded. That is also why there is no file size or file count limit: nothing costs us anything per conversion. The practical ceiling is your own device's memory, which on a phone means very large images may fail.
Will converting BMP to ICO reduce the quality?
No. Both BMP and ICO are lossless, so every pixel is preserved exactly.
What size should a favicon be?
This tool writes 16x16, 32x32 and 48x48 into a single .ico, which covers browser tabs, bookmarks and the Windows desktop. Start from a square image of at least 256x256 so the downscaled versions stay sharp, and keep the design simple — at 16 pixels, fine detail disappears entirely.
What is the difference between BMP and ICO?
BMP is Microsoft’s raw, uncompressed bitmap format — every pixel stored literally, with no compression at all. ICO is the Windows icon container, and the traditional format for a website’s favicon. In practice the choice comes down to compatibility: strong on Windows, weak everywhere else, and never used online. Meanwhile universal for its one job: favicons and Windows icons.