BMP to ICO converter
Drop in a BMP and get an ICO back. ICO is the icon file that Windows and browsers use, and it holds several sizes of the same picture in one file so nothing ever has to be stretched. Your file never leaves your computer.
Need the other direction? Convert ICO to BMP
How to convert BMP to ICO
- 1 Drop your BMP .bmp or .dib file onto the page, or click to browse for it.
- 2 Set the quality, or leave the default, which keeps the file small without anything showing.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the ICO, or add more files and do the whole set in one go.
Why convert BMP to ICO
- Holds several resolutions so the system never has to rescale.
- Still the most reliably recognised favicon format.
- Multi-resolution icon sets in a single file.
- BMP: files are enormous, often ten to fifty times a comparable PNG.
BMP compared with ICO
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | BMP | ICO |
|---|---|---|
| File extension | .bmp | .ico |
| Compression | Uncompressed | Lossy or lossless |
| Multiple pages | No | Yes |
| Colour depth | 1, 4, 8, 16, 24 or 32 bits per pixel | Up to 32-bit with alpha |
| Typical file size | Largest | Depends on mode |
| Browser support | All current browsers | Every browser |
| Introduced | 1986 | 1985 |
Quality and what changes
ICO stores the same content under a different set of rules, so what matters here is compatibility rather than picture quality. Convert once from the best source you have rather than through a chain of intermediate files.
- Each ICO entry is capped at 256 by 256 pixels.
- One ICO limitation to keep in mind: each picture inside it is capped at a small size.
Questions about BMP to ICO
Is there a maximum size for ICO?
Yes, ICO is limited to 256 x 256 pixels per entry. Images beyond that have to be scaled down or split before they can be written, which is a property of the format rather than of this tool.
Is my BMP file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your BMP is read straight from your own disk, converted on your machine and handed back as an ICO. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several BMP files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate ICO downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.