What's the difference between BMP and ICO?

BMP is a Windows-era uncompressed raster format. ICO is the Windows icon format and the classic home of the site favicon.ico.

Why convert away from BMP?

BMP is a Windows-era uncompressed raster format. Where it falls down: anything where file size matters (which is almost everywhere); web display, email, archive — pick literally any other format. ICO addresses that for most workflows.

When is ICO the right format?

ICO is a good choice for: site favicons (favicon.ico) and Windows application/shortcut icons; bundling several icon sizes in one file. It is a poor choice when photographs and general web images (use WebP, JPG, or PNG).

Anything surprising about BMP or ICO?

BMP can technically carry a small palette and run-length compression, but in practice 99% of BMPs in the wild are uncompressed. And on the ICO side: modern .ico files embed PNG frames; convert.now packs a single PNG frame per icon.

Does this work on mobile?

Yes. The drop zone falls back to your phone's file picker, and conversions run on-device just like desktop. Large files may be slower on mobile due to CPU and memory constraints, but the workflow is identical.

What's the maximum file size?

No hard limit — the browser handles it. Files under 50MB convert in a few seconds. Larger files work but may take longer as the browser allocates memory. If you hit issues, batch in smaller groups.

Convert BMP to ICO

Turn a BMP into a multi-resolution ICO favicon. BMP is uncompressed, so expect a dramatic size reduction. Free, in your browser.

Drop images to convert

PNG, JPG, WebP, AVIF, JPEG XL, TIFF, BMP, GIF, SVG, HDR, ICO — any combination

Files stay on your device. Open DevTools' Network tab to verify.

Output format

ICO

Overview

Why convert BMP to ICO

ICO is a more practical choice than BMP for most modern workflows: site favicons (favicon.ico) and Windows application/shortcut icons. Coming from BMP, the thing to know is that anything where file size matters (which is almost everywhere).

Comparison

BMP vs ICO: what actually differs

BMP compared with ICO across encoding, fidelity, file size and support.
Attribute	BMP	ICO
Compression	—	Lossless
Transparency	No	Yes
Animation	No	No
Typical file size	Very large	Varies
Browser support	Major browsers will render BMP, but it's never the right choice for the web.	Universally supported as a favicon — every browser reads .ico. Not used for general on-page images.

How to

How to convert BMP to ICO

01
Drop your BMP files
Drag one or more BMP files onto the dropzone above, or click to browse. Files stay on your device — nothing uploads.
02
Convert in your browser
convert.now decodes each BMP and re-encodes it as ICO via WebAssembly. The conversion runs in a Web Worker so the page stays responsive.
03
Download the result
Download a single ICO file or, for batch conversions, a zip of all converted files. Filenames preserve the originals.

Why here

Why convert.now

Private
Files stay in your browser. No upload step. Nothing for anyone to see.
Fast
No queue, no upload wait. Conversion starts the moment you drop a file.
Free
No ads. No file-count limit. No sign-up wall. Just the converter.

FAQ

BMP to ICO: common questions

No. The conversion from BMP to ICO runs entirely in your browser using WebAssembly. Files never leave your device. Open DevTools' Network tab if you'd like to verify — there are no network requests with file contents.

Related BMP converters

Last updated 27 August 2026

Why convert BMP to ICO

BMP vs ICO: what actually differs

How to convert BMP to ICO

Drop your BMP files

Convert in your browser

Download the result

Why convert.now

BMP to ICO: common questions

Related BMP converters