Roman Numeral to Number Converter

Convert Roman numerals to numbers with this free online calculator. Instantly convert any Roman numeral to its decimal value with step-by-step explanation.

Convert Roman Numerals to Numbers

Roman Numeral Table

M1000

CM900

D500

CD400

C100

XC90

L50

XL40

X10

IX9

IV4

Basic Roman Numerals

Special Combinations

Roman Numeral Reference Guide

Symbol	Value	Usage	Subtractive Rules
I	1	Can be repeated (III = 3)	Before V and X
V	5	Never repeated	No subtractive pairs
X	10	Can be repeated (XXX = 30)	Before L and C
L	50	Never repeated	No subtractive pairs
C	100	Can be repeated (CCC = 300)	Before D and M
D	500	Never repeated	No subtractive pairs
M	1000	Can be repeated (MMM = 3000)	No subtractive pairs

Common Combinations

IV = 4

I before V

IX = 9

I before X

XL = 40

X before L

XC = 90

X before C

CD = 400

C before D

CM = 900

C before M

Key Rules

1. Only use subtractive notation with I, X, and C

2. Never repeat V, L, or D

3. Can repeat I, X, C, and M up to three times

How to Read Roman Numerals

Reading Roman numerals follows a simple set of rules. Generally, you read from left to right, adding the values unless a smaller numeral comes before a larger one.

Basic Rules:

When a smaller numeral appears before a larger one, subtract the smaller value
When a smaller numeral appears after a larger one, add the values
The same symbol cannot be repeated more than three times in a row
Only I, X, and C can be used as subtractive numerals

For example, in "XIV" (14):

X = 10
I before V means subtract 1
V = 5
Therefore: X + (V - I) = 10 + (5 - 1) = 14

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