Convert BMP to ICO Online — Free & Private
Converting BMP to ICO re-encodes an image from Bitmap Image File / Device Independent Bitmap into Windows Icon. This free converter does it entirely inside your browser — your files are never uploaded — and handles unlimited batches with no sign-up, no watermark and no software to install.
Drag & drop your BMP files here
Batch conversion supported · up to 50 MB per file
🔒 Processed locally in your browser — nothing is uploaded.
How to convert BMP to ICO
To convert BMP to ICO: add your files to the converter above, confirm ICO is selected as the output format, press Convert, then download the result. The whole process runs in your browser and takes a few seconds.
- Add your files. Drag BMP files onto the box above, or click Choose files to browse. Multiple files at once are fine — there is no limit on how many.
- Check the settings. ICO is already selected. Quality is fixed because this target is lossless. Turn on Resize output if you need specific dimensions.
- Press Convert. Each file is decoded, redrawn and re-encoded on your device, with progress shown per file.
- Download. Take files individually, or use Download all as ZIP for the whole batch.
Why convert BMP to ICO?
Converting BMP to ICO usually comes down to compatibility or file size. Website favicons and Windows application icons, where several sizes must live in one file.
BMP vs ICO: what actually changes?
The practical differences are compression, transparency and compatibility. BMP is uncompressed with only in the rarely supported 32-bit variant transparency; ICO is container with supported at 32-bit colour depth transparency. The table below sets out every difference that affects the result.
| Property | BMP | ICO |
|---|---|---|
| Compression | Uncompressed | Container |
| Transparency | Only in the rarely supported 32-bit variant | Supported at 32-bit colour depth |
| Animation | Not supported | Not supported — the .ani format handles that |
| Colour depth | 1, 4, 8, 16, 24 or 32-bit | Up to 32-bit, including an alpha channel |
| Introduced | 1990 | 1985 |
| Browser support | Supported for display, but effectively never used on the web | Universal for favicons; the original favicon format |
| Typical size | Frequently 20–50× a JPG of the same image | Depends entirely on how many sizes are included |
| Best for | Legacy Windows software and embedded systems that need raw pixel data with no decoding step. | Website favicons and Windows application icons, where several sizes must live in one file. |
What is a BMP file?
BMP stands for Bitmap Image File / Device Independent Bitmap. Introduced in 1990 by Microsoft, it uses uncompressed compression and is best suited to legacy Windows software and embedded systems that need raw pixel data with no decoding step.
An uncompressed Windows bitmap. Enormous files, but dead simple — still used by some legacy Windows and embedded software.
| Property | BMP |
|---|---|
| Full name | Bitmap Image File / Device Independent Bitmap |
| File extensions | .bmp, .dib |
| MIME type | image/bmp |
| Introduced | 1990 |
| Developed by | Microsoft |
| Compression | Uncompressed |
| Colour depth | 1, 4, 8, 16, 24 or 32-bit |
| Transparency | Only in the rarely supported 32-bit variant |
| Animation | Not supported |
| Browser support | Supported for display, but effectively never used on the web |
| Typical file size | Frequently 20–50× a JPG of the same image |
BMP strengths
- Dead simple structure — trivial for any program to read
- No compression means no compression artefacts at all
- Long-standing support across Windows tooling
BMP limitations
- Enormous files — width × height × 3 bytes, with no compression
- Transparency support is inconsistent in practice
- Nobody uses it on the web, for good reason
What is a ICO file?
ICO stands for Windows Icon. Introduced in 1985 by Microsoft, it uses container compression and is best suited to website favicons and Windows application icons, where several sizes must live in one file.
The Windows and favicon format. Holds several square sizes in one file; 16×16, 32×32 and 48×48 are the sizes browsers actually reach for.
| Property | ICO |
|---|---|
| Full name | Windows Icon |
| File extensions | .ico |
| MIME type | image/x-icon |
| Introduced | 1985 |
| Developed by | Microsoft |
| Compression | Container |
| Colour depth | Up to 32-bit, including an alpha channel |
| Transparency | Supported at 32-bit colour depth |
| Animation | Not supported — the .ani format handles that |
| Browser support | Universal for favicons; the original favicon format |
| Typical file size | Depends entirely on how many sizes are included |
ICO strengths
- Stores multiple resolutions in a single file
- The most broadly compatible favicon format, including very old browsers
- Alpha transparency for non-square icon shapes
ICO limitations
- Restricted to icon-sized square images
- No use outside icons
- Larger than a single equivalent PNG, since it holds several copies
Does converting BMP to ICO lose quality?
No. ICO is lossless, so the conversion writes every decoded pixel exactly as it is. Note that any quality already lost inside the original BMP file cannot be recovered — lossless means nothing further is lost, not that damage is undone.
Two distinct things are often confused here. The first is whether the target format discards data: ICO is container, so it does not. The second is whether the source already lost data: BMP is uncompressed, so the source holds the original detail intact.
A practical rule: converting repeatedly between lossy formats compounds the damage each time. If you expect to edit an image more than once, work in a lossless format and export to a lossy one only at the end.
Is it safe to convert BMP files here?
Yes, and you can verify it rather than trust it. Your BMP file is read, decoded and re-encoded inside your browser tab. There is no upload endpoint on our side, so no copy of your image exists anywhere but your own device.
Most online converters upload your file to a server, process it there and promise to delete it later. That promise is unverifiable, and it does not survive a breach, a misconfigured storage bucket or a legal request. This tool removes the question entirely: the code comes to you, the file stays put.
To confirm it for yourself, open your browser’s developer tools, switch to the Network tab, and convert a file. You will see the page assets load and nothing carrying your image leave. It also works with your connection switched off entirely, once the page has loaded.
BMP and ICO at a glance
BMP files use the image/bmp MIME type and the .bmp extension; ICO files use image/x-icon and .ico. The summary below covers the properties that matter when choosing between them.
| BMP | ICO | |
|---|---|---|
| Full name | Bitmap Image File / Device Independent Bitmap | Windows Icon |
| Extension | .bmp, .dib | .ico |
| MIME type | image/bmp | image/x-icon |
| Year | 1990 | 1985 |
| Best for | Legacy Windows software and embedded systems that need raw pixel data with no decoding step. | Website favicons and Windows application icons, where several sizes must live in one file. |
BMP to ICO: frequently asked questions
- How do I convert BMP to ICO?
- Open this page, drag your BMP files onto the drop zone, and press Convert. ICO is already selected as the output format. The conversion runs in your browser and finishes in seconds, then you download the result individually or as a ZIP.
- Is this BMP to ICO converter free?
- Yes, completely. There is no account, no daily limit, no watermark and no paid tier. You can convert as many BMP files as you like, as often as you like.
- Are my BMP files uploaded to a server?
- No. The conversion runs entirely in your browser using the Canvas API and WebAssembly codecs. Nothing about your file is transmitted to us, so there is nothing for us to store, share or lose. You can verify this by opening your browser's Network tab while converting.
- Will converting BMP to ICO reduce quality?
- ICO is lossless, so every pixel that survives decoding is written exactly as it is. No further quality is lost in the conversion itself.
- Will the file get bigger or smaller?
- ICO files are typically depends entirely on how many sizes are included, against frequently 20–50× a jpg of the same image for BMP. The converter shows the before and after size for every file so you can see the exact result.
- Can I convert multiple BMP files at once?
- Yes. Drop the whole batch in and they convert one after another with individual progress. Download them one by one, or take the entire set as a single ZIP file built in your browser.
- Does ICO support transparency?
- Yes — supported at 32-bit colour depth. Transparent areas in your BMP file are preserved in the ICO output.
- Is there a file size limit?
- Each file is capped at 50 MB, because conversion happens in your browser's memory and very large files can crash a tab, particularly on phones. There is no limit on how many files you convert.
- Does it work on iPhone, Android, Mac and Windows?
- Yes. It runs in any modern browser on any operating system — there is nothing to install. Universal for favicons; the original favicon format.
- Do I need to install software or sign up?
- Neither. There is no download, no extension, no account and no email address required. Open the page and convert.
Related conversions
Need to go the other way? Try ICO to BMP. Other conversions involving these formats: