Roman Numerals Converter

Roman numerals use seven symbols — I (1), V (5), X (10), L (50), C (100), D (500), M (1000) — combined by the subtractive rule: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.

Still widely used today: clock faces, film sequels (Rocky IV, Star Wars IX), Super Bowl titles (LVIII), chapter numbers, copyright years in film credits, formal outlines. Our converter handles the full standard range 1–3999.

The decoder finds Roman numerals in your text and replaces them with digits. The encoder finds numbers and converts them to Roman numerals. Both work on mixed text — non-numeric, non-Roman content passes through unchanged.

The system's most famous limitation: it has no zero. Roman numerals record counts, not positions — there is nothing to write when there is nothing to count — and the absence of a zero (and of place value) is a large part of why arithmetic in Roman numerals is so painful, and why the Hindu-Arabic digits eventually replaced them for calculation everywhere.

Look at almost any clock face with Roman numerals and you'll find 4 written IIII, not IV — a centuries-old horological convention. Explanations vary (visual balance with VIII across the dial is the most common), but the practice is so entrenched that IIII on a clock is considered correct even though IV is the standard subtractive form everywhere else.

Length and value have nothing to do with each other: 1888 takes thirteen characters (MDCCCLXXXVIII) while 2000 takes two (MM) — and this year, 2026, is a tidy MMXXVI. The standard seven symbols top out at 3,999; scribes who needed more drew a bar (vinculum) over a numeral to multiply it by a thousand. For everything numerals are actually used for today — monarchs and popes, film sequels, Super Bowls, clock faces, credits — the 1–3,999 range has proved more than enough.