How Roman numerals work
Seven letters carry all the values: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1,000. Letters are added together from left to right, except when a smaller one comes before a larger one — then it is subtracted. IV is 4, IX is 9, XL is 40, CM is 900.
The rules
- Only I, X and C are ever subtracted, and only from the next two values up: IV and IX, XL and XC, CD and CM.
- A letter repeats at most three times: III is 3, but 4 is IV, not IIII.
- V, L and D never repeat and are never subtracted.
- There is no zero and no way to write a fraction or a negative number.
- Above 3,999 a bar over a letter multiplies it by a thousand — V̄ is 5,000.
Worked example
2026 is MMXXVI: two thousands, two tens, a five and a one. Reading backwards, MCMXCIV is 1994 — M is 1,000, CM is 900, XC is 90 and IV is 4.
How to use the converter
- Type a number to get the numeral, or type a numeral to get the number — it works out which you meant.
- Read the breakdown to see which letters produced which values.
- Tick the bar form if you need numbers above 3,999.
Where they are still used
- Clock faces, book chapters, film credits and the Super Bowl
- Monarchs and popes — Elizabeth II, Pius XII
- Outlines and legal documents, for numbered sections
- Tattoos of dates, which is why the converter checks your numeral is written the standard way
Frequently asked questions
What is 2026 in Roman numerals?
MMXXVI — two M for 2,000, two X for 20, V for 5 and I for 1.
Why is 4 written IV and not IIII?
Because a letter repeats at most three times, and a smaller letter before a larger one is subtracted. IIII does appear on some clock faces, but IV is the standard form.
How do you write numbers above 3,999?
With a bar over the letter, which multiplies it by 1,000 — V̄ is 5,000 and X̄ is 10,000. Tick the bar option above to use it.