Why convert BMP to ICO?

ICO is the format Windows expects for application icons, desktop shortcuts, and favicons. This lets you take a plain, often years-old BMP graphic and turn it into a real, multi-resolution .ico file ready to use.

Can I generate a multi-size ICO?

Yes. The ICO output defaults to a multi-size package covering 16, 32, 48, 64, 128, and 256 px, or you can pick a single size from the dropdown.

Will the ICO be smaller than the source BMP?

Generally, yes. BMP source files are normally stored uncompressed, and each ICO entry uses real PNG compression, so even a multi-size package bundling six images is often close to or smaller than the original uncompressed bitmap.

Does the source BMP actually carry usable alpha?

It depends on the file. Older BITMAPINFOHEADER-based BMPs have no alpha channel at all, while newer V4/V5-header BMPs can carry real per-pixel alpha — but not every BMP-writing tool sets it even when the header supports it. Whatever alpha the source actually has is what each ICO entry keeps.

Are my files uploaded?

No. Conversion runs locally in your browser and does not upload your file to Looty Tools servers.

What is validated before conversion?

The file must actually be a BMP — the tool checks the "BM" header bytes, not just the filename or extension, before decoding.

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BMP to ICO Converter

Convert BMP images to a Windows ICO icon directly in your browser — generate a single size or a multi-size icon package.

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BMP to ICO processes files locally in your browser.

What BMP to ICO conversion does

Turn an old BMP graphic into a Windows ICO icon directly in your browser. Generate a single size, or the default multi-size package covering 16, 32, 48, 64, 128, and 256 px in one .ico file — a common way to repurpose a legacy bitmap as an app icon or favicon.

How to convert BMP to ICO

Choose a BMP file.
Pick a single icon size, or leave the default multi-size package selected.
Select Convert & download.
Save the .ico file from your browser downloads.

Why use this conversion

ICO is the format Windows expects for application icons, desktop shortcuts, and favicons — so a plain BMP asset, however old, can be turned into a real, multi-resolution .ico file ready to use.

Transparency and output quality

Each embedded size keeps whatever alpha the browser decoded from the source BMP — real per-pixel alpha if the file used a V4/V5 header with transparency, none if it was an older BITMAPINFOHEADER-only file. This is a real ICO container (ICONDIR plus one entry per size), with each size embedded as genuine PNG-compressed image data, not a renamed bitmap. Since BMP source files are typically uncompressed, converting to ICO's PNG-compressed entries is a straightforward size win: a single-size ICO stays small; the multi-size package is larger only because it bundles six images.

Privacy and local processing

Processing occurs locally in the browser.
Files are not uploaded to Looty Tools for conversion.
Converted files remain on your device.

Limits and known issues

Input: BMP (.bmp) only, up to 25.0 MB and 8,192 px per side.
Each icon size is generated by resizing the full image to a square canvas, so a non-square source will be stretched to fit.
BMP files carry no metadata to bring along, so what you get is purely the pixel content resized into each icon slot — nothing else transfers.
Metadata is not preserved in the downloaded file.

Related tools

Guides

BMP to ICO FAQ

Why convert BMP to ICO?: ICO is the format Windows expects for application icons, desktop shortcuts, and favicons. This lets you take a plain, often years-old BMP graphic and turn it into a real, multi-resolution .ico file ready to use.
Can I generate a multi-size ICO?: Yes. The ICO output defaults to a multi-size package covering 16, 32, 48, 64, 128, and 256 px, or you can pick a single size from the dropdown.
Will the ICO be smaller than the source BMP?: Generally, yes. BMP source files are normally stored uncompressed, and each ICO entry uses real PNG compression, so even a multi-size package bundling six images is often close to or smaller than the original uncompressed bitmap.
Does the source BMP actually carry usable alpha?: It depends on the file. Older BITMAPINFOHEADER-based BMPs have no alpha channel at all, while newer V4/V5-header BMPs can carry real per-pixel alpha — but not every BMP-writing tool sets it even when the header supports it. Whatever alpha the source actually has is what each ICO entry keeps.
Are my files uploaded?: No. Conversion runs locally in your browser and does not upload your file to Looty Tools servers.
What is validated before conversion?: The file must actually be a BMP — the tool checks the "BM" header bytes, not just the filename or extension, before decoding.