How to use
- Type a number (e.g. 1994) or a Roman numeral (e.g. MCMXCIV) and it converts the other way automatically. Lowercase letters and Unicode numerals such as Ⅻ work too.
- Press This year to fill in the current year.
- Under Date in Roman numerals, pick a date to see it in day-month-year, month-day-year and year-month-day order — handy for engravings and tattoos.
The rules
| Symbol | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
- Add symbols from largest to smallest. VIII = 5 + 1 + 1 + 1 = 8.
- A smaller symbol before a larger one is subtracted. There are only six such pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
- No symbol repeats more than three times in a row. 4 is IV, not IIII; 40 is XL, not XXXX.
- V, L and D are never repeated.
The largest number these rules can write is 3,999 (MMMCMXCIX). There is no symbol for zero or negative numbers. Larger values were historically marked with a bar over a letter (×1,000), but that is not part of the standard form.
Examples
- 1994 = 1000 + 900 + 90 + 4 = M + CM + XC + IV = MCMXCIV
- 2024 = 1000 + 1000 + 10 + 10 + 4 = MMXXIV
- 3888 = MMMDCCCLXXXVIII — the longest numeral from 1 to 3999 (15 letters)
- December 25, 2024 = XII · XXV · MMXXIV (month · day · year)
Things to watch
- Clock faces often show 4 as IIII. If you enter an additive form like that, the tool reads its value (4) and shows the standard form (IV).
- Forms such as IC (99) or IIV (3) break the rules. 99 is XCIX.
- Date order varies: the US uses month-day-year, most of Europe day-month-year, and East Asia year-month-day. Double-check the order before engraving.
FAQ
Where are Roman numerals used today?
Clock faces, book chapters and volumes, copyright years in film credits, regnal names such as Elizabeth II, and Super Bowl numbers (LVIII = 58).
Can I work out a date first?
Use the date add calculator to find a date a number of days away, or the D-Day calculator, then convert it here.