Roman numbers calculator
Convert Roman numbers to Arabic and vice versa.

Beta version

This online calculator is currently under heavy development. It may or it may NOT work correctly.
You CAN try to use it. You CAN even get the proper results.
However, please VERIFY all results on your own, as the level of completion of this item is NOT CONFIRMED.
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Roman and arabic numbers - enter your number here

Roman number
Arabic number

Some facts

  • Numbers written in the Roman system consist of 7 letters: I(1), V(5), X(10), L(50), C(100), D(500), M(1000).
  • In the basic version, the maximum Roman digit (M) has the value of 1000. However, sometimes overline is used to multiply digit value by 1000.
  • To read the value of the Roman number we count value of digits from left to right, following the rule below:
    • if the current number is the same or greater than the next one, then we add it to the result value (e.g. XI gives 10 + 1 = 11),
    • if the current number is smaller than the next one, then we subtract it (e.g. IX gives 10 - 1 = 9).
  • Despite the spread of the Arabic system, Roman numerals can still be found in some traditional applications, e.g.
    • century numeration e.g. XXI means 21st century,
    • sometimes dates e.g. in cinematography or to mark date of building construction e.g. MMXVIII (2018),
    • names of rulers, e.g. Louis XVI, John Paul II,
    • names of historical events, e.g. World War II,
    • sometimes chapters numbering in books,
    • months numbering, e.g. 31.XII.2018 (31 December 2018).

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