This all-in-one online Roman Numerals Calculator converts any given roman numeral to decimal number or any decimal number to roman numeral. Enter a number in the respective field of the calculator and click the ‘Calculate’ button to get the number converted.
Roman numeral system
Roman numerals are represented by the following different letters: I, V, X, L, C, D and M. Which represent the numbers 1, 5, 10, 50, 100, 500 and 1000. These seven letters are used to construct thousands of different numbers. Roman numerals are usually written largest to smallest from left to right.
The Romans developed a system of subtraction according to which there can be no more than three same numerals written in a row. In case one has to use more symbols the subtractive principle is used. For instance, the Roman numeral for three is written as ‘III’. However, the numeral for four is not written as ‘IIII’ but rather as ‘IV’, i.e. with the use of numerals for one and five. Because the one precedes the five we subtract it making four.
Because the largest letter used is M and we can only stack three of the same numerals together the largest number we can make in Roman notation is 3999 (MMMCMXCIX). So our Roman Numerals Calculator can correctly work with numbers from 1 to 3999.
Related calculators
Check out our other math calculators such as Binary Number Converter.