Roman Numeral Converter
Number ⇄ Roman Numeral
Understanding Roman Numerals
Roman numerals use combinations of seven letters — I, V, X, L, C, D, and M — to represent numbers, still seen today on clock faces, movie sequels, monarch names, and outlines. Unlike our base-10 positional system, Roman numerals are additive and subtractive, built from a fixed set of symbol values.
Additive Notation
I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Symbols of equal or decreasing value are simply added together: VIII = 5+1+1+1 = 8.
Subtractive Notation
When a smaller-value symbol precedes a larger one, it's subtracted: IV = 5-1 = 4, IX = 10-1 = 9, XL = 50-10 = 40, CM = 1000-100 = 900.
Why 3,999 Is the Limit
Standard Roman numeral notation has no symbol larger than M (1,000), and repeating a symbol more than three times in a row isn't valid. This caps the largest standard representable number at MMMCMXCIX (3,999).
Still in Everyday Use
Roman numerals commonly appear on clock faces, Super Bowl numbering, chapter/outline numbering, and copyright years in film credits.
Key Takeaways
- No Zero: The Roman numeral system has no symbol for zero — it wasn't designed for positional arithmetic like our modern number system.
- Valid Range: This converter supports the standard range of 1 to 3,999 — larger values require non-standard notations like an overline (vinculum) for ×1,000.
- Case-Insensitive Input: Roman numeral input is automatically converted to uppercase — both "mmxxiv" and "MMXXIV" convert identically.