Roman Numerals
Type a number or a Roman numeral and the other side updates. Invalid numerals get a plain explanation of what’s wrong, and every result shows how it’s built.
Subtractive pairs: IV 4 · IX 9 · XL 40 · XC 90 · CD 400 · CM 900. A bar over a numeral multiplies it by 1,000.
How Roman numerals work
Seven letters carry values: I 1, V 5, X 10, L 50, C 100, D 500 and M 1,000. Write the number from the largest value down and add them up: 2026 is MM (2,000) + XX (20) + VI (6) = MMXXVI.
To avoid four of a kind, a smaller numeral placed directly before a larger one is subtracted. Only six pairs are used: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). So 1994 is M + CM + XC + IV = MCMXCIV, not MDCCCCLXXXXIIII.
Because M can only repeat three times, the standard system stops at 3,999. For larger numbers a bar (vinculum) over a numeral multiplies it by 1,000: V̅ is 5,000 and M̅ is 1,000,000. The converter writes thousands this way from 4,000 up.
Questions
How do you write 2026 in Roman numerals?
MMXXVI: MM for 2,000, XX for 20 and VI for 6. Press “This year” to convert the current year.
Why is 4 written IV and not IIII?
The subtractive rule puts I before V to mean 5 − 1. IIII does appear on many clock faces, a tradition kept for visual balance, but IV is the standard form.
What is the largest Roman numeral?
Without extra notation, 3,999 (MMMCMXCIX). With the overline (vinculum) for thousands, 3,999,999 can be written as M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX.
Is there a Roman numeral for zero?
No. The Roman system had no symbol for zero. Medieval scholars sometimes wrote N, for nulla, in tables.
How do I write a date in Roman numerals for a tattoo or engraving?
Convert the day, month and year separately and join them with dots or another separator, for example XXVI.IX.MMXXVI (day first) or IX.XXVI.MMXXVI (month first). The date panel does this in either order. Double-check the result before making anything permanent.