Roman Numeral Converter
Convert between Roman numerals and Arabic numbers.
Number → Roman
Roman → Number
Roman Numeral Reference
📘 How It Works
Symbol-Value Mapping
Roman numerals use 7 symbols: I(1), V(5), X(10), L(50), C(100), D(500), M(1000). Combinations extend the range to 3999.
Subtractive Notation
Smaller values before larger ones indicate subtraction: IV=4 (5-1), IX=9 (10-1), XL=40 (50-10), XC=90, CD=400, CM=900.
Number to Roman
Starting from 1000, repeatedly subtract the largest possible value and append its symbol. Continue until the number reaches zero.
Roman to Number
Read left to right: if current symbol is less than next, subtract it; otherwise add it. Sum all values for the result.
Validation
Only valid Roman numeral characters (I, V, X, L, C, D, M) are accepted. Invalid characters trigger an error message.
💡 Common Use Cases
Year Conversion
Convert years for formal documents, movie credits, or building cornerstones. 2024 = MMXXIV.
Book Chapters & Outlines
Academic papers and legal documents often use Roman numerals for major sections (Chapter I, II, III).
Clock Reading
Many clocks and watches display Roman numerals. Quickly convert to read unfamiliar numerals.
Royal & Papal Names
Understand numbering for historical figures: Queen Elizabeth II, Pope John Paul II, Louis XIV.
Super Bowl & Events
Major events like the Super Bowl use Roman numerals (Super Bowl LVIII = 58). Convert to verify.
Educational Learning
Students learning Roman numerals can check their homework and understand the conversion rules.