Roman Numeral Converter
Convert between Roman numerals and regular numbers
Quick Reference
Common Conversions
Recent Years
How Roman Numerals Work
Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). The basic rule is additive — symbols are placed left to right from largest to smallest, and you add their values: XVII = 10 + 5 + 1 + 1 = 17. The subtractive rule handles the numbers 4, 9, 40, 90, 400, and 900: a smaller symbol before a larger one means "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.
No symbol appears more than three times consecutively. This is why 4 is IV (not IIII) and 9 is IX (not VIIII). The exception is clocks, which traditionally use IIII for 4 instead of IV — a convention dating to medieval clock-making that has persisted purely through tradition. If you see IIII on a clock face, it is not wrong — it is deliberately archaic.
Where You Still See Roman Numerals
Super Bowl numbering (Super Bowl LXI = 61), movie sequels and copyright dates, outlines and lists (I, II, III as section numbers), clock faces, monarch names (King Charles III), papal names (Pope Francis I), building cornerstones and dedications, and academic use (Volume II, Chapter IX). The NFL temporarily abandoned Roman numerals for Super Bowl 50 because "Super Bowl L" looked awkward, then resumed with LI the following year.
What is the largest Roman numeral?
Standard Roman numerals max out at 3,999 (MMMCMXCIX). For larger numbers, a bar over a numeral multiplies its value by 1,000: V̄ = 5,000, X̄ = 10,000, M̄ = 1,000,000. This notation is rarely used in modern contexts.
Is there a zero in Roman numerals?
No. The Roman numeral system has no symbol for zero because it predates the concept of zero as a number. Roman numerals are a positional representation system that does not require a placeholder digit. The concept of zero was introduced to Europe through Arabic-Hindu numerals around the 12th century.