Roman Numeral Converter
Convert numbers to Roman numerals and back, with validation and rules.
roman.exe
How it works
M = 1000D = 500C = 100L = 50X = 10V = 5I = 1
- Add when a smaller numeral follows a larger one: VI = 6.
- Subtract when a smaller numeral comes first: IV = 4, IX = 9, CM = 900.
- Never repeat a numeral more than three times — that's why 4 is IV, not IIII.
How to use Roman Numeral Translator
- 01Type a number from 1 to 3999 to see its Roman numeral.
- 02Or type a Roman numeral to see its value — invalid forms are flagged.
- 03Copy the numeral with the button below.
About Roman Numeral Translator
Roman numerals use seven letters — I, V, X, L, C, D, M — for 1, 5, 10, 50, 100, 500, and 1000. A smaller letter after a larger one adds (VI = 6); before it, it subtracts (IV = 4).
The system has no zero and tops out at 3,999 in standard form, which is why this converter covers 1–3999.
Frequently asked questions
- Why is 4 written IV and not IIII?
- Standard form never repeats a numeral more than three times, so 4 uses subtraction: 5 minus 1.
- Is there a Roman numeral for zero?
- No — the Romans had no symbol for zero. Medieval writers later used 'N' (nulla), but it isn't classical.
- What about numbers above 3999?
- Classical notation uses an overline to multiply by 1,000, which plain text can't represent, so this tool stops at 3,999.
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