Free Roman Numeral Converter
Quick Tips
- • This tool runs entirely in your browser - your data stays private.
- • Press Ctrl+V (Cmd+V on Mac) to quickly paste text.
- • Use the Copy button to save your result to clipboard.
- • Bookmark this page for quick access!
Convert between Roman numerals and Arabic (decimal) numbers.
Your Recent Tools
Examples
MCMLXXXIV
1984
2024
MMXXIV
XLII
42
3999
MMMCMXCIX
Why Use This Tool?
What problems does this solve?
Converting Roman numerals requires knowing rules that most people have forgotten. This tool converts instantly in both directions for documents, outlines, and dates.
Common use cases:
- Converting dates on buildings and monuments
- Creating formal outlines and chapter numbers
- Understanding movie sequel and Super Bowl numbers
- Formatting clock and watch faces
- Learning Roman numeral rules
Who benefits from this tool?
Writers formatting formal documents. Historians reading dated materials. Students learning Roman numerals. Anyone encountering Roman numerals in the wild.
Privacy first: All conversion happens locally in your browser. Your numbers never leave your device.
Frequently Asked Questions
3,999 = MMMCMXCIX. Beyond this requires extended notation (overlines or other symbols) which varied historically. Standard ASCII typically stops at 3,999.
Subtractive notation (I before V) makes the number shorter and follows modern conventions. However, IIII is traditionally used on clock faces for balance and readability.
Modern rules say no - use IV. But IIII appears on many clock faces by tradition. Historic Romans actually used both forms.
A bar (overline) multiplies the value by 1000. V̄ = 5000, X̄ = 10000. This extends Roman numerals to larger numbers beyond 3999.
Tradition and style. Roman numerals look more formal and classic. Rocky IV feels different from Rocky 4. It also avoids confusion with other numbers in titles.
Mnemonics help: "I Value Xylophones Like Cows Do Milk" (I=1, V=5, X=10, L=50, C=100, D=500, M=1000).
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