Roman Numeral Converter-- Roman to Decimal & Back
Convert between Roman numerals and decimal numbers (1-3999).
Roman Numeral Converter Tool
Why Use Our Roman Converter?
1 to 3999
Full standard Roman numeral range.
Instant Results
Real-time conversion.
100% Secure
All local, no server.
Bidirectional
Both directions with swap.
One-Click Copy
Copy results instantly.
Free Forever
No signup, no limits.
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Roman Numeral Guide
Roman numerals originated in ancient Rome and are still used today for clock faces, book chapters, movie sequels, Super Bowl numbering, and formal documents. The seven basic symbols are: I=1, V=5, X=10, L=50, C=100, D=500, M=1000.
Numbers are formed by combining symbols using additive and subtractive rules. For example, VIII=8 (5+3), but IX=9 (10-1). The largest standard Roman numeral is MMMCMXCIX = 3999.