Roman Numerals — Converter & Complete Guide
Convert any number to Roman numerals and Roman numerals back to numbers. Full reference chart, rules, and common examples.
What Are Roman Numerals?
Roman numerals are a numeral system originating in ancient Rome, using combinations of letters from the Latin alphabet to represent numbers. The seven core symbols are I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Despite the development of the Hindu-Arabic numeral system (0-9) that we use today, Roman numerals remain in widespread use for clock faces, book chapter and page numbers, movie sequel titles, year numbering in film credits and copyright notices, Super Bowl numbering, and formal or ceremonial contexts.
How to Read Roman Numerals — The Rules
Additive rule: When a symbol of equal or greater value follows another, add the values. III = 1+1+1 = 3. XV = 10+5 = 15. CCC = 100+100+100 = 300.
Subtractive rule: When a symbol of smaller value appears immediately before a larger one, subtract the smaller from the larger. IV = 5−1 = 4. IX = 10−1 = 9. XL = 50−10 = 40. XC = 100−10 = 90. CD = 500−100 = 400. CM = 1000−100 = 900.
Repetition limit: No symbol may be repeated more than three times consecutively. IV is used instead of IIII for 4, and XL instead of XXXX for 40.
Roman Numerals 1 to 100 — Key Values
1=I, 2=II, 3=III, 4=IV, 5=V, 6=VI, 7=VII, 8=VIII, 9=IX, 10=X, 11=XI, 12=XII, 13=XIII, 14=XIV, 15=XV, 16=XVI, 17=XVII, 18=XVIII, 19=XIX, 20=XX, 30=XXX, 40=XL, 50=L, 60=LX, 70=LXX, 80=LXXX, 90=XC, 100=C.
Common Roman Numeral Years
Roman numerals for years are used in film copyright notices, building inscriptions, and formal documents: 1999=MCMXCIX, 2000=MM, 2001=MMI, 2010=MMX, 2020=MMXX, 2024=MMXXIV, 2025=MMXXV.