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Roman Numeral Converter

Convert numbers to roman numerals and roman numerals back to numbers, from 1 to 3999.

To convert roman numerals, enter a number to get its roman form, or a roman numeral to get its value. The converter covers 1 to 3999 and validates subtractive notation, so it rejects malformed input like IIII or IC and suggests the correct form.

Runs in your browser
Privacy
Runs entirely in your browser — nothing is uploaded
Cost
Free, unlimited, no sign-up

Frequently asked questions

Why is 4 written IV and not IIII?

Standard roman numerals use subtractive notation: a smaller numeral before a larger one is subtracted. IIII appears on some clock faces but is not the standard form, and this converter rejects it.

What is the largest roman numeral?

Using standard letters the maximum is 3999 (MMMCMXCIX). Larger values required a vinculum — an overline multiplying the numeral by 1000 — which has no standard plain-text representation.

How to use the roman numeral converter

  1. 1Enter or paste your value.
  2. 2Choose the direction.
  3. 3The result appears immediately — copy or download it.

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Put the working roman numeral converter on your own site. It runs in your visitors' browsers exactly as it does here — free, no account, nothing uploaded.

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