Roman Numeral Converter
Type a number or a Roman numeral — the other side updates as you type.
How it breaks down
The seven symbols
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | A single tally mark |
| V | 5 | Thought to represent an open hand — five fingers |
| X | 10 | Two hands, or a tally crossed at every tenth mark |
| L | 50 | From an older symbol that gradually became the letter L |
| C | 100 | Centum, Latin for hundred |
| D | 500 | Half of the archaic symbol for 1,000 |
| M | 1,000 | Mille, Latin for thousand |
The subtractive rule
When a smaller symbol appears before a larger one, it is subtracted: IV is 4, not 6. Only six subtractive pairs are valid in standard notation:
IV (4) · IX (9) · XL (40) · XC (90) · CD (400) · CM (900)
The rule is that only powers of ten (I, X, C) can be subtracted, and only from the next two higher symbols. IL for 49 is invalid — it is written XLIX. Clock faces are the famous exception, where 4 is traditionally IIII rather than IV, for visual balance against the VIII opposite.
What Roman numerals cannot do
- Zero. There is no symbol for it. The concept arrived in Europe with Hindu-Arabic numerals centuries later, and its absence is the single biggest reason Roman numerals lost.
- Negative numbers and fractions. The Romans handled fractions with a separate duodecimal system of dots and symbols, not with numerals.
- Arithmetic. Try long division with
MCMXCIV. Positional notation makes calculation mechanical; Roman numerals make it an exercise in memory. - Large numbers. Standard notation stops at 3,999. Beyond that you need the vinculum — an overline multiplying a symbol by 1,000, so V is 5,000.
Where they survive
Clock faces, book chapters and page prefaces, film copyright dates, monarch and pope regnal numbers (Elizabeth II, Benedict XVI), Super Bowl numbering, and the outline levels of formal documents. In each case the appeal is decorative or hierarchical rather than mathematical.
Frequently asked questions
What is 2026 in Roman numerals?
MMXXVI — MM (2000) + XX (20) + VI (6).
Why is 4 sometimes written IIII on clocks?
Tradition and visual symmetry. IIII balances the VIII directly opposite it on the dial, and it keeps the first four hours as pure I-groups. Big Ben is a notable exception that uses IV.
Is there a Roman numeral for zero?
No. The Romans had no symbol for zero at all — medieval scholars writing in Latin used the word nulla when they needed it.
What is the largest number in Roman numerals?
3,999 (MMMCMXCIX) in standard notation, because there is no symbol above M and no more than three may repeat. With the vinculum — an overline meaning ×1,000 — you can reach 3,999,999.
How do I know if a numeral is valid?
Symbols must run largest to smallest apart from the six legal subtractive pairs, I/X/C/M may repeat at most three times, and V/L/D may not repeat at all. This converter flags any numeral that breaks those rules.