Decimal → Roman
1 – 3999
—
Roman → Decimal
I – MMMCMXCIX
—
Roman Numeral Reference
| Symbol | Value | Note |
|---|
Convert decimal ↔ Roman numerals. See the step-by-step breakdown of every value.
| Symbol | Value | Note |
|---|
Roman Numeral Converter converts integers to Roman numerals and Roman numerals to integers. Enter any number from 1 to 3,999 (standard Roman numeral range) to get its Roman representation, or enter a Roman numeral string (like XIV or MCMXCIX) to see its decimal value. The tool shows the conversion step by step, breaking down each symbol's contribution.
Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), M (1000). The subtractive principle applies for six cases: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900). These six pairs prevent repeating a symbol more than three times (IIII → IV). Standard Roman numerals have no representation for 0 (zero didn't exist in the Roman number system) and cannot easily represent fractions.
Roman numerals appear today in: clock faces, copyright years on films and TV shows, Super Bowl designations (Super Bowl LIX), book preface page numbers, monarchs and popes (King Charles III), outlines and legal documents, and the Unicode character range U+2160-U+2188 for Roman numeral characters (Ⅰ Ⅱ Ⅲ etc.).
Convert 2026
Result: 2026 → MMXXVI (M=1000, M=1000, X=10, X=10, V=5, I=1)
Convert Super Bowl LIX
Result: LIX → 50+9 = 59 → Super Bowl 59 (2025)
Convert MCMXCIX
Result: MCMXCIX → 1000 + (1000-100) + (100-10) + (10-1) = 1999
What are the rules for Roman numerals?
Standard Roman numeral rules: (1) Symbols are generally written largest to smallest, left to right. (2) Subtractive notation: a smaller symbol placed before a larger one means subtract. Only I before V or X, X before L or C, C before D or M. (3) No symbol repeats more than 3 times consecutively (IIII → IV, XXXX → XL). (4) V, L, D are never repeated or used as subtractors. (5) The range is 1-3,999. Numbers above 3,999 traditionally used a vinculum (overbar) to multiply by 1,000, but this is rarely used today.
What is MMXXVI in decimal?
MMXXVI = M + M + X + X + V + I = 1000 + 1000 + 10 + 10 + 5 + 1 = 2026. This is the current year. Film copyright notices, major events, and monuments often use the year in Roman numerals — MMXXVI will appear on content produced in 2026.
Why can't Roman numerals represent 0?
The Roman number system evolved for counting and accounting in ancient Rome, where practical counting starts at 1 (you wouldn't count 'zero sheep'). The concept of zero as a number didn't reach Europe until the 9th-10th century (via Arab scholars who got it from Indian mathematicians). Without zero: no positional notation (where the '0' in 100 vs 10 changes value), no way to represent 'nothing', and arithmetic becomes extremely difficult. Roman numerals are additive, not positional — which is why the Romans used abacuses for calculation, not written arithmetic.
How are Roman numerals used in copyright notices?
Film and TV copyright notices traditionally use Roman numerals for the production year. This was originally done to obscure the age of the content — audiences might not immediately know when MCMXCVII (1997) was made without converting. Under modern copyright law, the year is required in copyright notices. The practice of using Roman numerals continues as tradition. Example: © MMXXVI BBC (2026). Note: U.S. copyright law doesn't require specific formatting for the year — Arabic numerals are equally valid.
What is the Unicode range for Roman numeral symbols?
Unicode includes dedicated Roman numeral characters at U+2160-U+2188: Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ Ⅺ Ⅻ Ⅼ Ⅽ Ⅾ Ⅿ (and lowercase ⅰ-ⅿ). These are for compatibility with legacy encodings — you should use regular ASCII letters (I, V, X, L, C, D, M) in modern text, not these Unicode code points. The Unicode Standard notes these were included for compatibility with East Asian character encodings that had them, not to represent a separate number system.