Roman Numeral Converter
Convert numbers to Roman numerals and back (1–3999) — instant and validated. Free and private, right in your browser.
Report a problemNumber to Roman numeral
Roman numeral to number
How to use
- Type a whole number from 1 to 3999 in the first box to see it as a Roman numeral.
- Type a Roman numeral (using I, V, X, L, C, D, M) in the second box to read it as a number.
- Both convert as you type. If something is out of range or not a valid numeral, you get a gentle note.
FAQ
What numbers can I convert?
Standard Roman numerals run from 1 (I) to 3999 (MMMCMXCIX). There is no zero and no native way to write numbers above 3999 with the basic letters, so the tool sticks to that classic range and tells you kindly if you go outside it.
How do Roman numerals work?
Seven letters have values: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. You add them up left to right, except when a smaller letter sits before a larger one (like IV = 4 or IX = 9), which means subtract. The tool checks that a numeral you type is written the proper way before accepting it.
Is anything I type sent anywhere?
No. The conversion is plain logic in your browser — nothing is uploaded or saved. It works offline and keeps your input private.