BMP to ICO Converter: Free, Private, No Upload

Convert BMP files to ICO in your browser. Lossless output, batch up to 20 files at once, no upload, no account, no watermark. Your files never leave your device.

BMP to ICO
Batch up to 20 files
No upload, no account
Metadata stripped

1Add up to 20 images
2Pick from 18 formats
3Download or copy the code

Processed on your device. Your images are never uploaded, and metadata is stripped. How we keep it private

How do I convert BMP to ICO for free?

Drop your BMP files into the tool above, choose ICO as output, and download the result. Everything runs in your browser, so nothing is uploaded and there is no limit or watermark. It works on Windows, Mac, Linux, ChromeOS, iOS and Android — anywhere you have a modern browser.

Price: Free, no credits and no daily cap
Account required: No
File uploaded to server: No, processed locally in your browser
Batch limit: Up to 20 files at once
Input format: BMP
Output format: ICO
Best for: ICO workflows, lossless quality, editing, printing
Works on: Chrome, Edge, Firefox, Safari, iOS and Android browsers
Privacy: No upload, no tracking, metadata stripped
Output quality: Lossless, exact pixels

How to convert BMP to ICO

1
Drop your BMP files
Drag up to 20 BMP files onto the page or click to choose them. Everything runs in your browser.
2
ICO is preselected
Output is already set to ICO. Adjust quality, resize or batch if you want.
3
Download
Save each ICO, or download all of them together as a ZIP.

BMP to ICO: what changes and when it makes sense

BMP is a Bitmap image format. It is best known for a simple structure that legacy programs and embedded systems can read without a decoder library. The main drawbacks are enormous files and no reliable transparency.

ICO is an Windows icon format. It is best known for packing several sizes (16, 32, 48, 256 pixels) into a single file. The main drawbacks are a maximum size of 256 by 256 pixels and little use outside icons.

BMP vs ICO at a glance

Property	BMP	ICO
Type	Raster image	Container format
Compression	Usually uncompressed (run-length encoding exists but is rare)	A container holding one or more bitmaps, each stored as BMP or PNG data
Transparency	None	Full alpha channel with soft edges
Animation	No	No
Colour depth	1 to 32 bits per pixel	Up to 32-bit colour with an 8-bit alpha channel
Support	Opens in browsers and most desktop software, but almost never used on the web	Supported by Windows and by browsers as a favicon, but most image viewers and editors do not open it directly
History	Created by Microsoft for Windows 1.0 in 1985 as the native bitmap format for the Windows Graphics Device Interface. The "BM" signature has been unchanged since then. Still used in embedded systems and legacy Windows software.	Introduced by Microsoft with Windows 1.0 in 1985. The modern 32-bit alpha version became standard with Windows XP (2001). Windows Vista (2007) added PNG compression inside ICO for icons larger than 48x48.

What actually changes in this conversion

Both BMP and ICO are lossless, so the pixels come through unchanged.
BMP has no alpha channel, so every pixel is already opaque.
ICO holds images up to 256 by 256 pixels. Larger sources are scaled down.
EXIF, GPS and camera data are stripped on every conversion. That is good for privacy, but you lose capture dates.

About BMP: history and technical details

Created by Microsoft for Windows 1.0 in 1985 as the native bitmap format for the Windows Graphics Device Interface. The "BM" signature has been unchanged since then. Still used in embedded systems and legacy Windows software.

Technical: File header 14 bytes (signature, size, reserved, offset) followed by DIB header (40+ bytes). Supports 1, 4, 8, 16, 24, 32-bit pixels. Rows padded to 4-byte boundaries. Pixels can be stored bottom-up or top-down. Optional RLE4/RLE8 rarely used.

Real-world size: A 12-megapixel photo is 36 MB as 24-bit BMP. As JPG it is 2-4 MB (90% smaller). A 1920x1080 screen at 32-bit BMP is 8.3 MB; as PNG 200-600 KB.

Popular tools: Windows Paint, IrfanView, XnView, ImageMagick, GIMP, Adobe Photoshop, embedded dev tools.

Alternatives: PNG (lossless, 5-20x smaller), TGA (game pipelines), TIFF (professional print), JPG (lossy, much smaller).

About ICO: what you get

Introduced by Microsoft with Windows 1.0 in 1985. The modern 32-bit alpha version became standard with Windows XP (2001). Windows Vista (2007) added PNG compression inside ICO for icons larger than 48x48.

Technical: Container holds 1-65535 images. Each entry has a 16-byte directory: width, height, colour count, planes, bit count, data size, data offset. Images are BMP (DIB) or PNG. Max dimension 256x256. Typical Windows icons use 16, 32, 48, 64, 128, 256.

Real-world size: A 6-size favicon.ico is typically 15-40 KB. A single 256x256 PNG favicon is 8-15 KB. Modern best practice uses separate files for 16, 32, 180 (Apple), 192, 512 (PWA).

Popular tools: IcoFX, GIMP, Adobe Photoshop (with plugin), ImageMagick, Favicon Generator, RealFaviconGenerator.

Alternatives: PNG (single size, widely accepted), SVG (sharp at any size), favicon.ico (still needed for legacy).

Browser and software compatibility

BMP: Opens in browsers and most desktop software, but almost never used on the web. ICO: Supported by Windows and by browsers as a favicon, but most image viewers and editors do not open it directly.

ICO is meant for favicons and Windows icons. It is not a general-purpose image format.

Why people move away from BMP

A 12 megapixel photo saved as 24-bit BMP is roughly 36 MB because pixels are stored almost raw.
BMP has no practical support for transparency, and almost no web workflow expects it.

Why people choose ICO

Browsers and Windows still look for favicon.ico at the root of a site by default.
One ICO file can carry several sizes, so tab icons, bookmarks and shortcuts all look sharp.
Windows shortcuts and application icons expect ICO.

Common mistakes with BMP

Using BMP on web pages — files are 10-20x larger than PNG with zero benefit
Expecting BMP transparency to work — most viewers ignore the alpha channel
Converting large BMPs without checking disk space — can fill your drive

Best practices for keeping quality

BMP is raw pixels, so the source has no compression damage. Convert at full size and choose the output quality freely.
Start from a square image of at least 256 by 256 pixels and keep the design simple, since it will often be shown at 16 by 16.
Keep a PNG or SVG copy. Modern browsers accept link rel="icon" pointing at PNG or SVG.
Resize before converting if the image will be shown small. A 4000 pixel photo displayed at 800 pixels wastes bytes in any format.
Check the result at 100 percent zoom, especially around text, edges and gradients, before you replace any originals.
Keep your original files. Conversions to a lossy format cannot be undone.
When you convert a set of images, use the same quality setting for the whole batch. The converter handles up to 20 files at once.

BMP to ICO questions

Quick answers about privacy, quality, supported formats, file limits and how ICO works.

Why convert BMP to ICO?

ICO is lossless. It keeps every pixel exactly. It is the safe choice when you plan to edit, print or need exact pixel data.

Will converting BMP to ICO lose quality?

No. ICO is lossless, so nothing is thrown away.

Does ICO keep transparency?

Yes. ICO supports full transparency, so transparent areas in your original are kept.

Are my files uploaded?

Never. Everything runs in your browser. Your files never leave your device. Open DevTools Network tab while processing — you will see no upload request.

Can I convert many files at once?

Yes, up to 20 files at once. Download them individually or all together as a ZIP.

Does the converter strip metadata?

Yes. Browsers do not pass EXIF data through a canvas, so GPS, camera model and dates are removed on every conversion. That is good for privacy.

Is it free?

Yes. No credits, no daily cap, no account, no watermark. The practical limit is your device memory.

What sizes should a favicon.ico have?

At minimum 16x16, 32x32, and 48x48. Modern best practice is to include 16, 32, 48, 64, 128, and 256 pixel versions in one ICO file. Browsers pick the size they need.

Your files never leave your device

No upload, no account, no tracking. Everything happens in your browser using the Canvas API and WebAssembly. You can confirm this in your browser's DevTools Network tab while the tool runs — no request carries your file. See why ToolDeck is different.