Roman Numeral Translator
Convert between Roman numerals and ordinary numbers.
Ancient numbers, modern conversion
Roman numerals use letters to represent numbers, and though rarely used for calculation now, they still appear on clocks, in book chapters, film credits and dates. This converts between Roman numerals and ordinary numbers in both directions.
Enter a Roman numeral or a number to convert it.
How the system works, and its limits
Roman numerals build numbers from a few letters — I, V, X, L, C, D, M — added together, with a clever subtractive twist where a smaller letter before a larger one means subtraction, so four is IV rather than IIII. This subtractive rule is what makes the system compact but also fiddly, since the ordering matters and there are rules about which subtractions are allowed. The system has real limitations that show why it was replaced for arithmetic: there is no zero, no easy way to represent very large numbers, and doing calculations with it is genuinely awkward compared to our place-value system. Still, converting is useful for reading dates on buildings, monarch and sequel numbers, and clock faces, where Roman numerals persist as a matter of style and tradition.
Questions & answers
How does the subtractive rule work?
A smaller letter before a larger one is subtracted — so four is IV (one before five) and nine is IX, which keeps the numerals compact.
Why aren't Roman numerals used for maths?
They have no zero, no easy way to show very large numbers, and calculating with them is awkward compared to our place-value system, which replaced them.
Is anything uploaded?
No. The conversion happens in your browser.