Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers (1 to 3,999,999) with a full reference chart.
About the Roman Numeral Converter
This Roman numeral converter works in both directions: type a number to get its Roman numeral, or type a Roman numeral to get the number back — with validation that rejects malformed numerals like IIII or IC. It supports 1 to 3,999,999, going far beyond the usual 3,999 limit by using vinculum notation, shown here with parentheses: (X) means 10,000 and (M) means 1,000,000.
Roman numerals build numbers from seven letters — I (1), V (5), X (10), L (50), C (100), D (500) and M (1000) — using addition, plus subtraction for the six special pairs IV, IX, XL, XC, CD and CM. The converter applies these classical rules strictly, so its output matches what you see on clock faces, movie copyright dates, book chapters and monument inscriptions.
A built-in reference chart lists the thirteen key values every conversion is made from, making the tool useful for students learning the system, teachers preparing worksheets, tattoo designs, wedding dates and decoding the year at the end of film credits.
How to Use the Roman Numeral Converter
- 1Enter a number (1 to 3,999,999) to see its Roman numeral instantly.
- 2Or type a Roman numeral like MMXXVI to convert it back to a number.
- 3For large values, read (X) as 10,000 — parentheses mean ×1,000.
- 4Copy either result, or check the reference chart below.
Frequently Asked Questions
What is 2026 in Roman numerals?
2026 is MMXXVI: MM = 2000, XX = 20 and VI = 6. Nearby years follow the same pattern — 2024 is MMXXIV, 2025 is MMXXV and 2030 is MMXXX. Years are among the most common uses of Roman numerals today, appearing in film credits, cornerstones and Super Bowl numbering.
How do you write 4 and 9 in Roman numerals?
4 is IV (one before five) and 9 is IX (one before ten) — subtractive notation, where a smaller numeral before a larger one is subtracted. The same idea gives XL (40), XC (90), CD (400) and CM (900). Only these six subtractive pairs are valid; IIII and VIIII are considered incorrect in standard usage.
Why do Roman numerals normally stop at 3,999?
Because M (1000) is the largest standard symbol and rules allow at most three repeats, MMMCMXCIX (3,999) is the ceiling. The Romans extended the system with a vinculum — an overline multiplying a numeral by 1,000. This converter represents that with parentheses, so (V) = 5,000 and (MMM)CMXCIXCMXCIX-style values reach 3,999,999.
Is IIII on clock faces a mistake?
No — it is a deliberate, centuries-old convention in clockmaking. Many clock dials, including famous ones, use IIII instead of IV for visual balance with VIII on the opposite side of the face. Outside horology, IIII is treated as invalid, and this converter follows the standard rules, so it accepts only IV for 4.
Why does the converter say my Roman numeral is invalid?
The tool validates by converting your input back and forth: numerals that break the classical rules — more than three repeats (XXXX), doubled five-symbols (VV), or illegal subtractions like IC or XM — are rejected. Check that you only use I, V, X, L, C, D, M and the six subtractive pairs IV, IX, XL, XC, CD, CM.