Handitab

Roman Numeral Converter

Convert numbers from 1 to 3999 to Roman numerals or Roman numerals back to numbers, one value per line, with validation of the form.

About Roman Numeral Converter

Roman numerals are a number system that writes values with the letters I, V, X, L, C, D, and M. This converter turns whole numbers from 1 to 3999 into standard subtractive notation (4 is IV, 900 is CM) and reads Roman numerals back to numbers, one value per line. A numeral is accepted only if it matches the standard form, so IIII or IC is rejected. Zero, negatives, fractions, and overline notation above 3999 are not supported.

Also known as: Roman Numeral.

How to use Roman Numeral Converter

  1. Type or paste into the "Number or Roman numeral" box, or press "Use example" to try it with sample data.
  2. The result appears below and updates as you type.
  3. Copy the result with the copy button, or download it as a file where that is offered.

Questions about Roman Numeral Converter

Why is 3999 the largest number?

Standard Roman numerals have no single symbol above M (1,000), and a symbol may repeat at most three times, so MMMCMXCIX is the limit. Larger values need an overline (vinculum) meaning times 1,000, which plain text cannot show.

Why is IIII rejected when clocks use it?

The converter accepts only the standard subtractive form, in which 4 is IV. IIII is an older additive variant that survives on clock faces. Convert the number 4 to see the standard spelling.

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