Convert Both Ways
Type in either field — the other one updates automatically.
About this Roman numerals converter
Roman numerals are still everywhere: Super Bowl numbers (Super Bowl LVIII = 58), clock faces, book chapters, movie copyright dates, outline headings and monarch names. This tool converts in both directions at once — type an Arabic number and see the Roman form, or type letters like MDCCLXXVI and get 1776.
The system uses seven letters: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. When a smaller letter stands before a larger one it is subtracted: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Everything else is addition read left to right.
The standard form tops out at 3999 (MMMCMXCIX), because classic notation has no symbol for 5000. The converter enforces that range and tells you when a value falls outside it.
Students most often meet Roman numerals in history lessons, on clocks and watches, and in movie copyright dates like ©MMXXVI.
Roman numerals quick reference
| Number | Roman | Why it matters |
|---|---|---|
| 4 | IV | Subtractive pair: 4 is IV, not IIII |
| 9 | IX | Subtractive pair for 9 |
| 40 | XL | 40 is XL, not XXXX |
| 90 | XC | 90 is XC |
| 400 | CD | 400 is CD |
| 2026 | MMXXVI | The current year in Roman numerals |
The rules of Roman numerals
Letters never repeat more than three times in a row — III, XXX, CCC, MMM are the limits. Instead of four repeats, the subtractive pair is used: the smaller letter before the larger one means subtraction, and only I, X and C can play that role, each only before the next two larger letters (I before V or X, X before L or C, C before D or M).
To read a numeral, walk right to left: if a letter is smaller than the one after it, subtract it; otherwise add it. So MCMXCIV = M(1000) + CM(900) + XC(90) + IV(4) = 1994.
Practice with the converter above: type 1994 and watch it become MCMXCIV, then try MMXXVI the other way round.
How to convert to Roman numerals
- Type a number or letters: Any integer from 1 to 3999, or a Roman numeral like MMXXVI.
- Read the other field: The converter fills the opposite form instantly.
- Check the rules below: The quick table and rule box explain every subtractive pair.
FAQ
Why is 4 written IV and not IIII?
Standard subtractive notation prefers IV, but some clock faces use IIII for symmetry — both exist in the wild, and converters assume IV.
What is the largest standard Roman numeral?
MMMCMXCIX = 3999. Larger values historically used a bar over a letter to multiply it by 1000, but that is rarely used today.
Is there a Roman numeral for zero?
No. The Roman system had no zero — medieval computists used the word nulla instead. That is one reason the positional decimal system replaced it.
Where do I need Roman numerals today?
Super Bowl numbering (LVIII = 58), monarch and pope names (Elizabeth II, Benedict XVI), movie credits, book prefaces, clock faces and school outlines.