Roman Numeral Calculator | Number to Roman Numeral Converter

Free online Roman numeral calculator. Convert numbers to Roman numerals and Roman numerals to numbers. Easy to use converter with instant results.

Convert Numbers to Roman Numerals

Roman Numeral Table

M1000

CM900

D500

CD400

C100

XC90

L50

XL40

X10

IX9

IV4

Common Roman Numeral Conversions

Numbers to Roman Numerals

90 = XC 100 = C 500 = D 1000 = M 50 = L 10 = X 5 = V 1 = I

Roman Numerals to Numbers

XX = 20 XL = 40 IV = 4 IX = 9 XC = 90 CD = 400 CM = 900

Roman Numeral Rules

Repetition

A numeral cannot be repeated more than three times consecutively

Example: III is valid, IIII is not

Subtraction

Only I, X, and C can be used as subtractive numerals

Example: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900)

Value Order

Numerals must be arranged in descending order, except for subtractive pairs

Example: XVII (17) is valid, IXX is not

Frequently Asked Questions

What is the largest number that can be written in Roman numerals?

Traditional Roman numerals can represent numbers up to 3,999 (MMMCMXCIX). Numbers larger than this require special notation.

Why can't some numbers be written in Roman numerals?

Roman numerals follow specific rules about character repetition and order. Some numbers require notation that would break these rules.

Are Roman numerals still used today?

Yes, Roman numerals are still used in various contexts including book chapters, clock faces, movie sequel titles, and formal documents.

About this Calculator