How do Roman numerals work?

Roman numerals use letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. Letters are added together, but a smaller letter before a larger one is subtracted, so IV is 4 and IX is 9.

What is the largest Roman numeral?

Using the standard letters, the largest commonly written value is 3,999, or MMMCMXCIX. Beyond that, bars over letters were used to multiply by a thousand. This converter handles 1 to 3,999.

Is there a zero in Roman numerals?

No. The Roman system has no symbol for zero, which is one reason it is awkward for arithmetic. It starts at one, written I.

Roman Numeral Converter

This tool converts numbers into Roman numerals and Roman numerals back into ordinary numbers, so you never have to work out the rules by hand. Roman numerals still turn up on clock faces, in film and television credits, on building cornerstones, in book chapter and volume numbers, and for naming monarchs and popes. In the first field, enter any whole number from 1 to 3,999 and the converter instantly shows the matching Roman numeral, built from the seven letters I, V, X, L, C, D and M, standing for 1, 5, 10, 50, 100, 500 and 1,000. In the second field, type or paste a Roman numeral and it converts straight back into an ordinary number. The converter applies the two rules that govern the system: letters are normally added together from largest to smallest, but when a smaller letter sits immediately before a larger one, its value is subtracted instead, which is why IV reads as 4 rather than 6 and XC reads as 90 rather than 110. Because the classic Roman system has no symbol for zero and becomes unwieldy above 3,999, results outside that range are not shown, so check your number falls within it. Use it to check a date before it goes on an invitation, confirm a chapter numbering scheme, or simply satisfy your curiosity about how a particular year is written in Roman numerals.

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Number to Roman numeral

Number (1 to 3999)

MMXXVI

Roman numeral

Roman numeral to number

Roman numeral

number

The rules

The letters are I, V, X, L, C, D, and M for 1, 5, 10, 50, 100, 500, and 1000. You add them up from largest to smallest, but when a smaller letter sits before a larger one it is subtracted, which is how IV is 4 and XC is 90.

Worked example

2026 is MMXXVI: two thousands (MM), two tens (XX), a five (V), and a one (I). The year 14 is XIV: ten (X) plus four (IV).

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