Free webp to jpg
EN
Image MIME Reference
DWG

AutoCAD Drawing

image/vnd.dwg
VS

Windows Icon (Legacy MIME)

image/x-icon
ICO

A complete technical comparison of AutoCAD Drawing and Windows Icon (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

ICO wins on browser support

Feature Support

Feature DWG ICO
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
AutoCAD Drawing
image/vnd.dwg
Extension
.dwg
Container DWG Binary Container
Compression Proprietary Binary Compression (LZ77 based in newer versions)
Algorithm
Proprietary (Autodesk ObjectDBX)
Color Depth Vector (True Color / Indexed AutoCAD Color Index)
Developed by Autodesk
Released 1982
Magic Bytes
41 43 31 30 (AC10)
Full DWG reference →
Windows Icon (Legacy MIME)
image/x-icon
Extension
.ico
Container ICO Directory Structure
Compression Uncompressed (DIB/BMP) / Deflate (Embedded PNG)
Algorithm
NoneDeflate (via PNG)
Color Depth 1-bit, 4-bit, 8-bit, 24-bit (True Color), 32-bit (RGBA)
Developed by Microsoft Corporation
Released 1985
Magic Bytes
00 00 01 00
Full ICO reference →

Browser Support Comparison

Browser DWG ICO
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
DWG

DWG Strengths

  • The undisputed industry standard for 2D drafting and basic 3D CAD modeling
  • Highly optimized binary structure keeps file sizes relatively small compared to text-based CAD formats like DXF
  • Supports incredibly complex datasets including external references (XREFs), dynamic blocks, and extensive custom metadata
Limitations
  • It is a closed, proprietary format, making it difficult for third-party developers to support fully without licensing the Open Design Alliance (ODA) SDK
  • Lacks native web or standard operating system previewer support
  • Format versions change frequently (roughly every 3 years), breaking backward compatibility for older CAD software
ICO

ICO Strengths

  • Universally supported by every web browser in existence for website favicons
  • Packs multiple resolutions into a single file, eliminating the need to serve different files for the taskbar vs. the desktop
  • Modern support for embedded PNGs (since Windows Vista) allows for excellent 32-bit transparency (alpha channels) and drastically reduced file sizes
Limitations
  • Internal file structure is convoluted due to decades of legacy cruft, such as the requirement for BMP data to lack a standard file header but double the height property for an archaic XOR/AND mask
  • Larger file size compared to a single optimized PNG or SVG, as it literally stores the same image multiple times at different scales
  • The MIME type landscape is highly fragmented (x-icon vs. vnd.microsoft.icon), causing occasional caching or strict-MIME validation errors on restrictive servers

When to choose which format

DWG
Use DWG when…
  • Architectural Floor Plans
  • Mechanical Engineering Models
  • Civil Engineering Drafts
  • 3D Product Designs
ICO
Use ICO when…
  • Website Favicons (favicon.ico)
  • Windows Application Executable Icons (.exe)
  • Desktop Shortcut Icons

More comparisons

DWG vs ACES → ICO vs ACES → DWG vs APNG → ICO vs APNG → DWG vs AVCI → ICO vs AVCI → DWG vs AVCS → ICO vs AVCS → DWG vs AVIF → ICO vs AVIF → All comparisons →
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