CONVERT
ICO → BMP
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Fast, secure ICO to BMP conversion. No registration required.
ICO is the Windows icon container with multiple resolutions packed into one file. Reaching a BMP from there is one hop. Need a BMP for a CMS, a chat message or an email client that politely refuses ICO? This tool re-encodes your image in the background and returns a drop-in BMP replacement. No registration, no watermark, no visual change beyond what the BMP encoder itself introduces. In practice ICO is the Windows icon container with multiple resolutions packed into one file. On the other end, BMP is the uncompressed Windows bitmap format — bulky but pixel-perfect.
ICO Icon
Source formatICO is the icon file format used for favicons and Windows application icons. A single ICO file can contain multiple image sizes and color depths for different display contexts.
BMP Image
Target formatBMP is an uncompressed raster image format native to Windows. Files are large but preserve exact pixel data with no compression artifacts. Rarely used on the web due to file size.
Why convert ICO to BMP
Converting keeps the picture recognisable end-to-end while changing the container that ships it. BMP typically wins on one of three fronts: broader software support, smaller files for the same visual quality, or features like transparency that ICO cannot express. The conversion itself is fast because both sides are raster formats.
HOW TO CONVERT
ICO → BMP
Upload your ICO
Start by dropping the ICO onto the uploader. Files up to 25 MB go through on the free tier without registration; paid plans go up to 2 GB.
Conversion happens server-side
Our imagemagick-based pipeline reads the ICO pixel grid, preserves resolution and colour profile, and encodes a clean BMP.
Grab the result
A download button appears as soon as the BMP is ready. Save locally or share the short-lived URL.
Common Use Cases
Share across platforms
Send BMP files to anyone without worrying about whether they have the right software for ICO.
Embed in documents
Drop BMP output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
BMP often produces smaller files than ICO for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
ICO vs BMP — Strengths and limitations
What each format does best, and where it falls short.
ICO Strengths
- Multi-resolution: one file, many sizes, OS picks the right one.
- Universal favicon support in every browser since IE5.
- Supports transparency (1-bit since 1985, full alpha since XP).
- Tiny file size — an entire favicon pack typically fits in under 15 KB.
- No licensing or patent concerns — fully in the public domain spec-wise.
Limitations
- Cannot compress continuous-tone images efficiently — use PNG or WebP for photos.
- Format is essentially frozen in 1999 — no HDR, no wide gamut, no modern features.
- Maximum image dimension is 256×256 px (inside an ICO container).
BMP Strengths
- Dead-simple format — trivially easy to read and write.
- Lossless and uncompressed — perfect bit-exact pixel storage.
- Universally supported in Windows applications since 1985.
- Supports 1, 4, 8, 16, 24, and 32-bit color depths.
Limitations
- Enormous file sizes — no meaningful compression in typical use.
- Not a web format — browsers support it but nobody serves BMPs over HTTP.
- No metadata support (no EXIF, no ICC profile in practice).
ICO vs BMP — Technical specifications
Side-by-side comparison of the technical details.
ICO
- MIME type
- image/vnd.microsoft.icon
- Max resolutions per file
- 65 535 images
- Max single image size
- 256×256 px
- Color depths
- 1, 4, 8, 24, 32 bits per pixel
- Compression
- Uncompressed bitmap or embedded PNG (Vista+)
BMP
- MIME type
- image/bmp
- Color depths
- 1, 4, 8, 16, 24, 32 bits per pixel
- Compression
- None (typical); RLE 4/8 bit (rare)
- Extensions
- .bmp, .dib
- Byte order
- Little-endian
| Specification | ICO | BMP |
|---|---|---|
| MIME type | image/vnd.microsoft.icon | image/bmp |
| Max resolutions per file | 65 535 images | — |
| Max single image size | 256×256 px | — |
| Color depths | 1, 4, 8, 24, 32 bits per pixel | 1, 4, 8, 16, 24, 32 bits per pixel |
| Compression | Uncompressed bitmap or embedded PNG (Vista+) | None (typical); RLE 4/8 bit (rare) |
| Extensions | — | .bmp, .dib |
| Byte order | — | Little-endian |
ICO vs BMP — Typical file sizes
Approximate file sizes for common scenarios.
ICO
- Classic favicon (16×16 only) < 2 KB
- Multi-size favicon pack (16/32/48/256) 5-15 KB
- Full Windows app icon set 20-100 KB
BMP
- Small icon (32×32) 4 KB
- Screenshot (1920×1080) ~6 MB
- 4K image (3840×2160) ~25 MB
- Scanned A4 at 300 dpi ~25 MB
Quality & Compatibility
Converting keeps resolution, aspect ratio and colour profile identical to the source. Metadata (EXIF, XMP) transfers where BMP supports it; otherwise it is dropped. If the ICO contained an alpha channel and BMP does not support transparency, the background is flattened to white by default.
Tips for Best Results
- When uploading to Retina / high-DPI contexts, render the BMP at 2× the CSS pixel size; the crispness gap over 1× is noticeable on modern screens.
- Strip EXIF metadata from the BMP before publishing if the ICO came from a phone camera — it often contains GPS coordinates and device IDs.
- If the ICO is a screenshot of text or UI, prefer a lossless BMP target to avoid the JPEG-style ringing around glyph edges.
Frequently Asked Questions
It depends on the codecs involved. If both ICO and BMP are lossy, the pixels are re-encoded and a small amount of detail is discarded — invisible at default quality settings on photographs. If BMP is lossless (PNG, TIFF, BMP) the output keeps every pixel of the decoded ICO exactly, but cannot recover detail that ICO had already compressed away.
Often yes, especially when BMP is lossless. ICO tuned for efficient web delivery will usually produce smaller files than BMP's default settings. If file size matters, drop the quality in Advanced or pick a more compressed target format instead.
KaijuConverter uploads over HTTPS, processes the image in an isolated container and deletes both the source and the output within two hours. No account is required, file contents are never logged, and we do not use uploads to train any model. For confidential material, the paid plan includes a data-processing agreement.
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Read guideSecure & Private Conversion
Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.