Roman Numeral Converter

Convert between Arabic numbers and Roman numerals, in either direction. Enter a number (1 to 3999) or a Roman numeral.

Converted
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To the other form.

Usage Tip

Read left to right: when a smaller symbol comes before a larger one (IV, IX), subtract it; otherwise add.

THE MATH
Built from M(1000) D(500) C(100) L(50) X(10) V(5) I(1)
Subtractive pairs: IV(4), IX(9), XL(40), XC(90), CD(400), CM(900)
Roman numerals combine letters additively, with a smaller letter before a larger one meaning subtraction.
The standard system covers 1 to 3999.
Type a number to get the numeral, or a numeral to get the number.
Numbers must be between 1 and 3999.
Non-standard numerals are still read, with the standard form noted.
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