Roman numeral converter
Type a number (1 to 3999) or a Roman numeral and get the conversion instantly. The tool detects automatically what you have typed.
It detects the direction automatically. Supported range: 1 – 3999.
| Symbol | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
The seven letters behind everything
Roman numerals are built from just seven symbols: I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). Combining them writes any number. The general idea is to add from left to right: VIII is 5 + 1 + 1 + 1 = 8, and MMXXIV is 2024.
The subtraction rule, the one that confuses most
When a smaller symbol comes before a larger one, you subtract instead of adding. That's why IV is 4 (5 − 1) and IX is 9 (10 − 1). But you can't subtract just anything: only I, X and C may be placed in front to subtract, and only from the symbol immediately above. So 4 is IV and 40 is XL, but you never write IL or IC. V, L and D, by contrast, are never subtracted and never repeated.
What you can't do
No symbol is repeated more than three times in a row: 4 isn't IIII but IV, and 40 isn't XXXX but XL. There's also no symbol for zero, because the Roman system never had one. And in their usual form, Roman numerals run up to 3,999 (MMMCMXCIX); for larger figures a bar was placed over a symbol to multiply its value by a thousand.
Where they're still alive
Although we no longer calculate with them, they're everywhere: centuries (the 21st century), the names of kings and popes (Elizabeth II), some clock faces, film credits, the volumes of a series or the acts of a play. Being able to read and write them is useful more often than you'd think.