How Roman numerals work
Seven letters carry the values I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Reading left to right you add them up, except that a smaller numeral placed before a larger one is subtracted: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400, CM is 900. Those six pairs are the only subtractions allowed in the standard form; 99 is XCIX, not IC, and 4 is IV, not IIII (clock faces are the famous exception).
- Split the number into thousands, hundreds, tens and units: 1994 = 1000 + 900 + 90 + 4.
- Write each part with its own letters: M, CM, XC, IV.
- Join them: MCMXCIV.
Rules the validator checks
- I, X, C and M may repeat up to three times in a row; V, L and D never repeat.
- Only I, X and C can be subtracted, and only from the next two larger numerals (I before V or X, X before L or C, C before D or M).
- The standard system stops at 3999 (MMMCMXCIX). Larger values historically used a bar over a numeral to multiply by 1000, which this converter does not produce.
Where you still meet them
Film and TV copyright years (MMXXVI), monarchs and popes (Elizabeth II), Super Bowls, book front matter, clock faces, and outline numbering. Reading a copyright year in the credits is the most common reason anyone looks these up, so the table of recent years below the tool is there for that.
Questions
What is 2026 in Roman numerals?
MMXXVI: MM (2000) + XX (20) + VI (6).
Why is 4 written IV and not IIII?
The subtractive form is the standard since the Middle Ages. IIII survives on clock faces for visual balance with VIII on the other side, and on some older inscriptions.
Is there a Roman numeral for zero?
No. The Romans had no symbol for zero; the word nulla was used in some medieval texts. The converter starts at 1.
How do I write 4000 or larger?
Classically with a vinculum (a bar) over the numeral: V̅ is 5000, X̅ is 10,000. Fonts and inputs rarely support it, which is why most converters, including this one, stop at 3999.