Roman Numerals Converter
Convert numbers to Roman numerals and Roman numerals back to numbers, with a symbol-by-symbol explanation of the addition and subtraction rules.
Frequently Asked Questions
How do Roman numerals work — addition and subtraction rules?
Roman numerals use seven symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Addition rule: symbols of equal or decreasing value are added (VI = 5+1 = 6; XVII = 10+5+1+1 = 17). Subtraction rule: a smaller symbol placed before a larger one is subtracted (IV = 5−1 = 4; IX = 9; XL = 40; XC = 90; CD = 400; CM = 900). Only I, X, and C can be subtracted, and only from the next two larger values (I before V and X; X before L and C; C before D and M).
What are the rules for repeating Roman numeral symbols?
I, X, C, and M can be repeated up to three times in succession (III = 3; XXX = 30; CCC = 300; MMM = 3000). V, L, and D can never be repeated — you would use the next step instead (e.g. 10 is X, not VV). These repetition limits are why the standard system only reaches 3,999 (MMMCMXCIX). Writing MMMM for 4,000 violates the three-repetition rule, which is why vinculum notation (a bar over a symbol multiplying by 1,000) was used for larger numbers in antiquity.
What is the largest number representable in standard Roman numerals?
In standard subtractive notation, 3,999 = MMMCMXCIX is the upper limit. For larger numbers, a bar (vinculum) over a symbol multiplies it by 1,000: V̄ = 5,000; X̄ = 10,000; M̄ = 1,000,000. The year 2024 in Roman numerals is MMXXIV. The Super Bowl numbering uses Roman numerals — Super Bowl LVIII (58) was played in 2024. Roman numerals had no concept of zero, which limited their use in advanced mathematics.
Where are Roman numerals still used in the modern world?
Roman numerals remain in common use in specific contexts: film and TV credits (release year, copyright: © MMXXIV); clock faces (especially analogue watches and public clocks); book prefaces, outlines, and chapter numbering; monarchs and popes (King Charles III, Pope Francis I); sporting events (Super Bowl LVIII, Olympic Games); architectural inscriptions and cornerstones; sequels (Rocky II, Godfather Part III); music album track listings (side I, side II); and legal/formal documents.
How do you convert a large number like 1994 or 2024 to Roman numerals?
1994: 1000=M + 900=CM + 90=XC + 4=IV → MCMXCIV. 2024: 2000=MM + 20=XX + 4=IV → MMXXIV. Strategy: work from largest to smallest symbols. For each position, choose the correct subtractive pair or repeated symbol: thousands (M), hundreds (CM/D/CD/C/XC/L/XL/X), tens (IX/V/IV/I). 1776 = MDCCLXXVI; 2000 = MM; 1900 = MCM; 1776 = MDCCLXXVI. The subtractive combinations to memorise: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900.