Convert between Roman numerals (I, V, X, L, C, D, M) and Arabic numbers. Supports values from 1 to 3,999. Click any reference value to load it instantly.
This is a free, two-way Roman numeral converter: type an Arabic number to get its Roman form, or paste a Roman numeral to read it back as an ordinary number. It covers the standard range from 1 (I) to 3,999 (MMMCMXCIX) and validates every entry against the canonical Roman numeral grammar, so you always get a correct, well-formed result.
Roman numerals show up far more often than most people expect. People use it to:
Everything runs local and in-browser. Your numbers are converted instantly on your own device, nothing is uploaded to a server, and the tool keeps working even after you go offline.
Roman numerals build a number by adding up letter symbols from largest to smallest. You write the symbols in order and total their values, so MMXXIV is 1000 + 1000 + 10 + 10 + (5 - 1), which equals 2024.
Each letter has a fixed value: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. Every Roman numeral is made by combining these seven symbols.
When a smaller symbol comes directly before a larger one, you subtract it. So IV is 5 - 1 = 4 and IX is 10 - 1 = 9. The only valid subtractive pairs are IV, IX, XL, XC, CD, and CM.
It supports 1 up to 3,999, which is MMMCMXCIX. Larger values traditionally used an overline (a bar over a symbol to multiply it by 1,000), and that notation is not reliably displayed in plain text.
The Roman system was designed for counting and tallying, not positional place value, so it never needed a symbol for zero. There is also no way to write negative numbers or fractions in standard Roman numerals.
Your input is checked against the canonical Roman numeral grammar: V, L, and D never repeat, M, C, X, and I repeat at most three times in a row, and only the standard subtractive pairs are allowed. Lowercase letters are automatically uppercased for you.
They remain common for stylistic and formal numbering: clock faces, book chapters and outlines, movie copyright years, monarch and pope names, and event numbering such as the Olympics and the Super Bowl.