Free Roman Numeral Converter
Convert any number to Roman numerals — or decode Roman numerals back — instantly.
Result
How to use the roman numeral converter
- Type a number between 1 and 3999 and press To Roman.
- Or type a Roman numeral (like MMXXIV) and press To Number.
- Invalid numerals are flagged with an explanation.
How Roman numerals work
Roman numerals are built from seven letters: I (1), V (5), X (10), L (50), C (100), D (500), M (1000). You generally add values left to right, but a smaller numeral before a larger one subtracts — so IV is 4, not 6, and XC is 90. The subtractive trick only applies to specific pairs (IV, IX, XL, XC, CD, CM), which is why this converter validates input instead of guessing. Classical Romans had no zero and no concept of numbers above a few thousand in this system, which is why the converter caps at 3999 (MMMCMXCIX). You will still see Roman numerals on clock faces, book chapters, movie sequels, and the occasional Super Bowl.
Frequently asked questions
What is 2024 in Roman numerals?
MMXXIV — that is 1000 + 1000 + 10 + 10 minus 1 + 5... more precisely M + M + XX + IV.
Why does it stop at 3999?
Traditional Roman numerals have no standard way to write 4000+ (Romans used a bar over letters for thousands). MMMCMXCIX is the largest standard form.
Is IIII ever correct instead of IV?
On clock faces, yes — clockmakers traditionally used IIII for 4, likely for visual symmetry with VIII. Everywhere else, IV is standard.
How do you read CMXCIX?
CM (900) + XC (90) + IX (9) = 999. Read the subtractive pairs first, then add.