Browser-onlyLiveGeneral Calculators
Roman Numeral Converter
Convert between Roman and Arabic numerals in the 1 - 3999 range.
Privacy note. Runs in your browser. The numerals you enter aren't logged or sent anywhere.
Roman numeralMMXXVI
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Frequently asked questions
Standard Roman notation only goes up to MMMCMXCIX (3999) using the seven letters I, V, X, L, C, D, M. Larger numbers historically used overlines or other extensions which this calculator does not implement.
IIII is not canonical: the standard subtractive form for four is IV. The calculator round-trips your input through the canonical converter and flags any string that does not match exactly.
Yes. Lowercase Roman numerals are converted to uppercase before being parsed, so "mmxxvi" and "MMXXVI" both decode to 2026.
Last updated 2026-06-03.