How to Read Roman Numerals (Chart & Rules)
Roman numerals still appear on clocks, book chapters, film credits and monuments. They use just seven letters and two simple rules. Once you know them, you can read almost any numeral at a glance.
The seven symbols
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
The add rule
When symbols run from largest to smallest, you add them together. So MDCLXVI is 1000 + 500 + 100 + 50 + 10 + 5 + 1 = 1666. Repeated symbols also add — III is 3 and XXX is 30 — but a symbol is never repeated more than three times in a row.
The subtract rule
To avoid four repeats, a smaller symbol placed before a larger one is subtracted. That gives IV = 4, IX = 9, XL = 40, XC = 90, CD = 400 and CM = 900. Only these six subtractive pairs are valid, so 99 is written XCIX, not IC.
A worked example
Read MCMXCIV in chunks: M = 1000, CM = 900, XC = 90, IV = 4, which totals 1994. Working left to right in groups like this is the fastest way to decode a long numeral.
Quirks and limits
There is no zero and no way to write fractions or negatives, and standard numerals stop at 3999 (MMMCMXCIX). One charming exception to the rules: most clock faces show four as IIII rather than IV, a long-standing tradition usually explained by visual balance with the VIII opposite it.
Convert instantly
To turn a number into a numeral, use the Roman Numeral Converter; to decode a numeral back into a number, the Roman Numeral to Number tool does it in one step.
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Last updated: July 6, 2026