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ICO to BMP Converter
Extract the largest image from a Windows ICO file and save it as a BMP. Here is the odd part: BMP is the format ICO is most closely related to, and it is also the one that throws away the most — because BMP has no usable transparency and icons nearly always have some.
Drag and drop your ICO images here
Add several at once. Each file is processed and then deleted from our server.
Up to 20 MB per file Batch ready
BMP cannot store transparency, so it is filled with this colour.
Conversion queue
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Step by step
How to convert ICO to BMP in 3 steps
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Add your .ico file
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Choose a background colour
Choose a background colour for the areas that were transparent. White is the default.
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Download your BMP
Format comparison
ICO vs BMP
ICO (Windows Icon)
Multi-size iconBundles several sizes of the same small image in one file, for Windows icons and website favicons.
- Several icon sizes in a single file
- Understood by every browser as a favicon
- Only for small images — each entry is at most 256 × 256 pixels
BMP (Windows Bitmap)
UncompressedAn early Windows format that stores pixels more or less raw, with little or no compression.
- Read by old and embedded software that knows nothing newer
- No compression artefacts
- Very large files for the image size
The closest relative loses the most
ICO and BMP are family. Both came out of mid-1980s Windows, and the images inside an ICO have traditionally been device-independent bitmaps — BMP data without its file header. The pixel formats line up almost exactly.
Which makes the shortfall surprising. ICO gained transparency early: first a one-bit mask, later a full alpha channel, because an icon has to sit on a desktop of unknown colour. BMP never really did. A 32-bit BMP with alpha is technically possible and is almost never what tools produce or expect.
So converting an icon to its nearest relative discards the one thing the icon most needed. The transparent area becomes a solid rectangle of whatever colour you pick, and that choice is permanent.
If you do not specifically need BMP, ICO to PNG keeps everything and opens everywhere.
You get the largest image in the file
An ICO holds several sizes — commonly 16, 32, 48 and 256 pixels. The largest is extracted, which is what anyone recovering artwork wants.
Some converters take the first entry instead, which is frequently the 16×16. That produces a valid file containing a postage stamp, with no error to tell you what happened.
Expect a large file
BMP stores pixels raw, with no compression in practice. A 256×256 icon becomes roughly 260 KB regardless of content — a plain white square costs exactly as much as detailed artwork.
For comparison, the same image as PNG is typically a few kilobytes, since icon artwork is flat colour and compresses beautifully. If size matters at all, BMP is the wrong target.
Semi-transparent edges
The smooth edges of an icon are made of partly-transparent pixels. Flattening blends them into your chosen background, so they end up permanently tinted with it.
Match the colour to wherever the image will actually sit. An icon flattened onto white and then placed on a dark background shows both a white rectangle and a pale fringe around the artwork.
What happens to transparent pixels when converting ICO to BMP?
BMP cannot store transparency, so transparent and semi-transparent areas are blended onto a solid background before the file is saved — the colour you choose above, #FFFFFF by default. Keep your original ICO if you may need the transparency again.
Quality
Quality and file size
There is no quality setting. BMP stores pixels exactly as given, so nothing is compressed and nothing is lost beyond the transparency discussed above.
When BMP is genuinely the right answer
Rarely, but the cases are real:
- Legacy Windows tooling that reads BMP and nothing else — still common in installers, industrial software and older development toolchains.
- Embedded systems where a trivial format is preferred because implementing a decoder is not worth it.
- Software that draws its own bitmaps and expects raw pixel data.
- Testing and debugging, where an uncompressed file can be inspected directly.
Outside those, PNG does the same job better in every measurable way.
Colour depth
The output is standard 24-bit colour, which every tool reads. If your target software needs a lower depth — some very old systems want 256 colours — you will need an editor that can write that specifically.
Do not enlarge it
The extracted image is at most the largest size stored in the icon, usually 256 pixels. An ICO holds no vector information, so scaling up produces a soft blocky picture. For larger artwork you need the original design file.
Where this comes up
Almost always legacy work. Someone is maintaining or rebuilding older Windows software, the toolchain wants a BMP, and the artwork exists as an icon.
- Installer graphics, where BMP remains the conventional format for banners and backgrounds.
- Resource files in older development environments.
- Industrial and embedded displays that only decode bitmaps.
- Legacy applications whose asset pipelines were written decades ago and still work.
Plan the background colour
This is the decision that matters, because it cannot be undone. Before converting, find out what colour the image will actually sit on:
- An installer banner — match the banner's background, not white.
- A dialog or toolbar — match the system control colour it will sit against.
- Unknown — white is the least-bad default, but consider whether you can use PNG instead and avoid the choice entirely.
The three ways out of an ICO
- PNG — keeps transparency, small, opens everywhere. The right answer unless something forbids it.
- WebP — keeps transparency, smallest of all, ideal for websites.
- BMP — this page. Loses transparency, largest file. For legacy tooling that accepts nothing else.
Going the other way
BMP to ICO builds a multi-size icon from a bitmap, which is the other half of most legacy workflows.
What happens to your file
Browsers cannot read the ICO container, so this runs on our server. Your upload is deleted the moment conversion finishes, the result is deleted as you download it, and anything abandoned is swept automatically.
Privacy
What happens to your file
This tool runs on our server, so it works the same on every phone and computer. Your file is uploaded, and this is exactly what happens to it:
- Stored outside the public web root under a random name, never under your file's name.
- Processed, with the original upload deleted immediately — whether it succeeded or failed.
- The result sits behind a signed link that only you receive, which stops working after 20 minutes, and the file is deleted the moment you download it.
- Anything never collected is deleted automatically within 30 minutes.
- The image itself is never logged or kept. If a conversion fails, we record the formats involved and the error — not the file.
- Camera metadata, including any GPS coordinates recording where a photo was taken, is removed from the result. Only the rotation needed to show the image the right way up is kept.
Questions & answers
ICO to BMP: frequently asked questions
Why does the closest format lose the most?
Because of one specific gap. ICO and BMP are family — the images inside an ICO have traditionally been bitmaps without their file header — but ICO gained transparency early, first as a mask and later as a full alpha channel, because icons sit on desktops of unknown colour. BMP never really did. So the nearest relative discards the one thing the icon most needed.
Which image is extracted?
The largest in the file, which is what anyone recovering artwork wants. Some converters take the first entry instead, frequently the 16×16 — producing a valid file containing a postage stamp, with no error to explain it.
Why is the BMP so large?
BMP stores pixels raw with no compression in practice, so a 256×256 icon is around 260 KB whatever it contains — a plain white square costs the same as detailed artwork. The same image as PNG is typically a few kilobytes, because icon artwork is flat colour and compresses beautifully.
What background colour should I pick?
Whatever the image will actually sit on, because the choice is permanent. For an installer banner, match the banner. For a dialog or toolbar, match the system control colour. The smooth edges of an icon are made of partly-transparent pixels, and they end up permanently tinted with whatever you choose.
Should I use BMP at all?
Only when something specifically requires it — legacy Windows tooling, installer graphics, embedded displays, or software that expects raw pixel data. Outside those cases PNG does the same job better in every measurable way, and keeps the transparency.
Can I get a 256-colour BMP?
Not from here — the output is standard 24-bit colour, which every tool reads. If your target software specifically needs a lower depth, you will need an editor that can write that.
Keep going
Related image tools
ICO to PNG Converter
Convert Windows ICO files to PNG, keeping transparency. Extracts the largest image the icon contains.
BMP to ICO Converter
Convert BMP to a multi-size Windows ICO icon. The two formats share a lineage, which explains what carries across and what does not.
ICO to WebP Converter
Extract an ICO to WebP with transparency intact. The smallest of the three options, and the right one for putting old icon artwork on a website.
BMP to PNG Converter
Convert BMP to PNG with no quality loss at all. Typically 70-90% smaller, and perfect for screenshots and pixel art.