Roman Numeral Converter
Convert a number to Roman numerals, or Roman numerals back to a number.
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About this tool
Standard Roman numerals use seven symbols (I, V, X, L, C, D, M) combined additively, with a subtractive shorthand for four cases in each order of magnitude (IV instead of IIII, IX instead of VIIII, and so on for X/C and C/M). This tool supports the standard range of 1–3999 — beyond that, Roman numerals traditionally need a special overline notation (multiplying a symbol by 1,000) that has no reliable plain-text representation.
"Roman → Number" validates that the input is well-formed standard notation, not just any combination of the seven letters — IIII or VX, for example, are rejected as invalid rather than silently guessed at. Nothing you enter here is sent to a server — the entire tool runs as JavaScript in your browser tab.