Convert Arabic Numbers to Roman and Back
Online calculator — enter the values and get the result instantly, with the formula and a worked example.
Roman numerals are a way of writing numbers using letters of the alphabet.
This method of writing Roman numerals originated in the Middle Ages. It is derived from the way the ancient Romans wrote numerals, but includes some improvements. The basic Roman numerals used today are: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000
The Romans typically wrote the number 4 as IIII, the number 40 as XXXX, and the number 999 as DCCCCLXXXXVIIII.
To shorten the notation of such long numbers, a subtraction rule was used. The subtraction rule allows the use of six composite symbols, where the smaller numeral precedes the larger: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900
Enter Arabic number
Enter Roman number
Worked example
Conversely, we need to convert the Roman numeral MCCLIV to an Arabic number. We use the subtraction rule mentioned above with the six composite symbols as described.
Then MCCLIV breaks down to:
M = 1000
CC = 2 * 100
L = 50
IV = 4
Total: 1254
