Math
Roman Numerals Converter
Convert between Roman numerals and Arabic numbers (1 to 3999). Auto-detects direction, validates strict subtractive notation, and shows a reference table.
Roman numerals converter
Direction is detected automatically. Roman numerals must be uppercase and within 1 to 3999.
Arabic
2,026
Roman
MMXXVI
Reference table
I
1
V
5
X
10
L
50
C
100
D
500
M
1,000
Subtractive pairs: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
Frequently Asked Questions about the Roman Numerals Converter
What is subtractive notation in Roman numerals?
Subtractive notation places a smaller symbol before a larger one to mean subtraction. Only six pairs are valid: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). That is why 4 is IV rather than IIII, and 1994 is MCMXCIV rather than MDCCCCLXXXXIIII.
Why is MMMM not a valid Roman numeral?
The standard system allows at most three of the same symbol in a row. Three M's give you MMM (3000), so the highest valid number is MMMCMXCIX (3999). Values from 4000 up require non-standard extensions like overlines, which this converter does not support, so any number outside 1 to 3999 returns no result.
How do you write zero in Roman numerals?
You cannot. The Roman system grew from tally marks, where the absence of a count was simply not recorded, so no symbol for zero was ever defined. Around 725 AD the monk Bede (or a colleague) used the letter N, from the Latin nulla or nihil for nothing, but that is a stand-in, not a numeral, which is why this converter only accepts integers from 1 to 3999.
Where are Roman numerals still used today?
They appear on Super Bowl branding (Super Bowl LIX is 59), clock faces, book prefaces and chapter headings, movie sequels (Rocky IV), royal and papal names (Elizabeth II, Pope John XXIII), and copyright dates at the end of films and TV broadcasts.
How do I read Roman numeral dates on old buildings?
Work left to right and add each symbol's value, except when a smaller symbol precedes a larger one, where you subtract it instead. For example, MDCCLXXVI breaks down as M (1000) + D (500) + CC (200) + L (50) + XX (20) + V (5) + I (1) = 1776, the year of US independence.