Roman Numerals Converter

Roman to Arabic numeral converter - fast and error-free online conversion

Roman to Arabic numeral converteris an easy-to-use online tool that converts the traditional Roman numeral system (I, V, X, L, C, D, M) into the Arabic numerals we know well today. You paste or enter a Roman number, click "Convert" and immediately get the correct result - without counting "on foot" and the risk of error.

The tool will be useful for all those who work with historical texts, analyze inscriptions, prepare teaching materials, as well as for people who simply want to quickly check what a given Roman writing means on a clock, building or in a book.

Launch Roman Number Converter

What are Roman Numbers and How Do They Work?

Roman numeralsare a historical number writing system used in ancient Rome, based on letter combinations of the Latin alphabet. Instead of ten digits (0-9), we use seven symbols:

Combinations of these letters allow you to write both small and very large numbers - from simpleII(2), throughXIV(14), up toMCMXCIV(1994) orMMXXIV(2024).

Rules for writing Roman numbers - the most important rules

To read and write Roman numbers correctly, it is worth knowing a few key rules. Our converter has them "built-in" - it checks the correctness of the entry and calculates the result on this basis.

• Adding symbols– when symbols go from larger to smaller, the values are added:VI = 5 + 1 = 6, XVII = 10 + 5 + 1 + 1 = 17.
• Subtraction of symbols– if a smaller symbol is in front of a larger one, it is subtracted:IV = 5 − 1 = 4, IX = 10 − 1 = 9.
• Repeating characters- symbolsI, X, C, Mcan be repeated a maximum of three times in a row:III = 3, XXX = 30, MMM = 3000.
• Limitations when subtracting– not every smaller symbol can appear before every larger one. Example of correct entries:IV(4),IX(9),XL(40),XC(90),CD(400),CM(900).
• No zero– the Roman system does not have the symbol for 0, which distinguishes it from the modern decimal system.

The Roman numeral converter applies these rules in the background, so you can immediately see whether the given notation is correct and what value it represents in the Arabic system.

How does the Roman to Arabic number converter work?