Roman numeral converter
Type a number for the numeral, or a numeral for the number.
- Runs in your browser — your text is never sent anywhere
- No sign-up, no quotas, free to use as often as you like
How it works
Roman numerals turn up in film credits, clock faces, book chapters, monarch names and tattoos. Reading a long one correctly takes more care than people expect, because the subtractive pairs do not behave like ordinary digits.
It works out which way round you meant
Type digits and you get the numeral; type letters and you get the number. There is no mode to choose.
The subtractive rule
IV is four, not six, because a smaller numeral before a larger one is subtracted. Only I, X and C are used this way, and only before the next two larger symbols — which is why 99 is XCIX and not IC.
Non-standard spellings
Numerals like IIII, which appears on many clock faces, are readable but not the conventional spelling. Where what you typed differs from the standard form, both are shown rather than the input being rejected.
The 3999 limit
Classical Roman numerals stop at 3999. Larger values used an overline meaning “multiply by a thousand”, which cannot be represented in plain text, so larger numbers are refused rather than spelled wrongly.
Roman numeral converter — questions
Why is 99 XCIX and not IC?
Subtraction only applies to the next two larger symbols, so 99 is XC (90) plus IX (9).
Why can it not go past 3999?
Larger values needed an overline to multiply by a thousand, which plain text cannot represent.
Is IIII wrong?
It is non-standard but readable, and common on clock faces. The standard form is shown alongside.