Convert Roman Numerals

Convert Roman numerals to Arabic numerals and vice versa quickly and easily.


Enter the Roman numeral you want to convert in the Roman numerals field, and the answer will be immediately displayed in the Arabic numerals field. To perform the conversion in reverse, you can click the swap button to switch the positions of the fields or directly enter a different number in either of the two fields.

Standard form of Roman numerals

Roman numerals are constructed using a specific set of letters from the Roman alphabet. These letters are combined according to specific rules to represent numbers. Here's how Roman numerals are constructed:

  • I: Represents the number 1.
  • V: Represents the number 5.
  • X: Represents the number 10.
  • L: Represents the number 50.
  • C: Represents the number 100.
  • D: Represents the number 500.
  • M: Represents the number 1000.

The rules for constructing Roman numerals are as follows:

  1. Numbers are read from left to right, and their values are added together.
  2. If a letter of lesser value appears before a letter of greater value, you must subtract the value of the smaller number from the larger number. For example, IV represents 4 (1 less than 5) and IX represents 9 (1 less than 10).
  3. If a letter of lesser value appears after a letter of greater value, you must add the value of the smaller number to the larger number. For example, VI represents 6 (5 plus 1) and XII represents 12 (10 plus 2).
  4. No more than three consecutive repetitions of the same letter should be used. If you need to represent a larger number, a horizontal bar is placed over the letter to multiply its value by 1000. For example, V̅ would be 5000.
  5. The letters V, L, and D cannot be repeated within a number. There are no numbers like VV or LL in the Roman system. To represent numbers like 5000, a horizontal bar is used over the corresponding letter: V̅ for 5000, L̅ for 50,000, and D̅ for 500,000.

Here are some examples of Roman numerals:

III represents 3.

VII represents 7.

XVI represents 16.

XL represents 40 (10 less than 50).

XC represents 90 (10 less than 100).

CCXLIV represents 244 (100 plus 100, minus 10, plus 50, plus 1, plus 1, plus 1).

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