Convert ICO to BMP
Output is typically roughly 360× larger.
- Files stay on your device
- Free, no sign-up
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Will converting ICO to BMP make the file smaller?
Usually, yes. A 12-megapixel photo is around 100 KB as ICO and around 36 MB as BMP — roughly 360× larger. Because BMP is lossless the result depends entirely on the image content — flat colour and text compress far better than photographic detail.
Does converting ICO to BMP lose quality?
No. BMP is lossless, so every pixel decoded from your ICO file is stored exactly. Both formats are lossless, so the conversion is pixel-for-pixel identical.
Is transparency preserved when converting ICO to BMP?
Yes. Both ICO and BMP support an alpha channel, so transparent and semi-transparent pixels carry across unchanged — a logo with a cut-out background stays cut out, and soft drop shadows keep their gradient rather than picking up a white halo. Because BMP is lossless, the alpha channel is stored exactly as it was.
Why are BMP files so large?
BMP stores pixels essentially uncompressed — three or four bytes per pixel with no encoding at all. A 12-megapixel photo therefore lands around 36 MB, roughly 11× the same image as a JPEG. That simplicity is deliberate: legacy Windows software and embedded devices can read BMP with almost no code.
What kind of BMP does this produce?
An uncompressed 32-bit BMP with a BITMAPV4 header, which is the variant that carries an alpha channel reliably — plenty of BMP writers emit 24-bit files where transparency is silently dropped. Uncompressed means large: expect roughly four bytes per pixel, so a 12-megapixel photo lands around 48 MB regardless of what it started as.
How it works, and more about ico to bmp
How it works
- Add your ICO file. Drag a ICO file onto the drop zone, or click to browse. You can select several at once.
- Choose your settings. BMP is lossless, so there is nothing to configure — the output matches the input pixel for pixel.
- Download the BMP. Conversion runs on your device as soon as each file is added — no upload, no queue. Download each result when it is ready.
ICO and BMP side by side
| ICO | BMP | |
|---|---|---|
| Full name | Windows Icon | Bitmap Image File |
| Compression | Lossless | Lossless |
| Transparency | Yes — alpha channel | Yes — alpha channel |
| Animation | No | No |
| Browser support | Universal for favicons | Supported in all major browsers, though rarely used on the web |
| Typical 12 MP photo | ~100 KB | ~36 MB |
| Usually used for | Website favicons and Windows application icons | Legacy Windows applications, scanners and embedded displays |
On a typical 12-megapixel phone photo, the BMP output comes out roughly 360× larger than the ICO original. These are order-of-magnitude figures for one kind of image — your own results will vary a great deal, because flat colour, text and line art behave nothing like photographic detail.
What this tool actually produces
Not estimates. Each row below was produced by running the file through this page in a real browser and measuring the result, at the default quality of 82.
| Test image | ICO in | BMP out | Change |
|---|---|---|---|
| Logo with transparency 512 × 512, flat colour on a transparent background | 264 KB | 256 KB | -3% |
Every test image got smaller, though by very different margins — flat colour and text behave nothing like photographic detail, so treat the closest row to your own content as the useful one. Measured in Chrome 150.0.7871.46; other browsers encode slightly differently.
What to watch out for
- Massive files — often 10× a JPEG of the same image
- No animation, and inconsistent transparency support across variants
- Impractical for the web or for sharing
About the two formats
ICO is a container rather than a codec: it bundles the same icon at several sizes — typically 16, 32, 48 and 256 pixels — so the operating system or browser can pick the right one. Its remaining job is the favicon at the root of a website, and Windows application icons.
BMP stores pixels essentially uncompressed, which makes it enormous — a 12-megapixel photo lands around 36 MB, roughly 11× the same image as a JPEG. It persists mainly inside legacy Windows software, scanning utilities and embedded systems where decoding simplicity beats file size.
Other conversions
Everything runs on your device — nothing is uploaded, so there is no size limit, no queue and no copy left on a server afterwards. There is more on how browser-based conversion works if you want the detail. Otherwise, browse every image tool, or convert BMP back to ICO.