Roman Numeral Converter

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Convert numbers to Roman numerals and back, from 1 to 3999. See a place-by-place breakdown and instant validity checks. Free and accurate.

Enter a whole number from 1 to 3999.
Enter a valid Roman numeral, e.g. MMXXIV.
Result –
Breakdown
  • –
Roman numerals run from I (1) to MMMCMXCIX (3999).

About Roman Numeral Converter

The Roman numeral converter changes ordinary numbers into Roman numerals and back again, covering the full classical range from 1 (I) to 3999 (MMMCMXCIX). Type 2026 to get MMXXVI for a tattoo, cornerstone or movie copyright line, or paste a numeral like MCMLXXXIV to decode the year it represents.

To make the system easy to learn, the converter shows a place-by-place breakdown — thousands, hundreds, tens and ones — so you can see how MMXXIV assembles from MM, XX and IV. Conversions are validated live: out-of-range numbers and malformed numerals such as IIII or VX are flagged immediately with a clear message.

It is a free, instant reference for students, designers, genealogists and anyone checking clock faces, book chapters, Super Bowl numbers or dates carved on buildings. Everything runs in your browser as you type.

How to use Roman Numeral Converter

  1. Choose the direction: number to Roman, or Roman to number.
  2. Enter a whole number from 1 to 3999, or type a Roman numeral such as MMXXIV.
  3. Read the result and check the thousands/hundreds/tens/ones breakdown.

Frequently asked questions

Standard Roman notation has no single symbol beyond M (1000) and repeats a letter at most three times, so MMMCMXCIX (3999) is the largest well-formed numeral. Larger values historically used an overline, which is outside the standard system.

MMXXVI — two thousands (MM), two tens (XX) and six (VI). Enter any year and the breakdown panel shows exactly how each place value contributes to the numeral.

Placing a smaller symbol before a larger one subtracts it: IV is 4 and IX is 9. Only I, X and C may be used subtractively, and only before the next two larger symbols — the validator enforces these rules.

IIII is a traditional variant seen on clock faces, but standard modern notation writes 4 as IV. The converter follows the standard rules, so IIII is flagged as invalid.

Yes — case does not change the value. mcmxcix and MCMXCIX both decode to 1999; the converter reads the letters, not their capitalization.
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