Roman Numeral Converter

Roman numerals are built from seven letters — I (1), V (5), X (10), L (50), C (100), D (500), M (1000) — combined by addition and, for four specific cases, subtraction. Type a number or a numeral into either box and this converts both directions at once, showing exactly which symbols make up the result.

How the symbols combine

Symbols are normally added left to right in descending value: VI is 5+1=6. But a smaller symbol placed before a larger one subtracts instead — IV is 5−1=4, not 4 written as IIII. Only six subtractive pairs are standard: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900). 1984 breaks down as M (1000) + CM (900) + LXXX (80) + IV (4) = MCMLXXXIV.

Where the year 2026 fits

2026 converts to MMXXVI — MM (2000) + XX (20) + VI (6) — no subtractive pairs needed since none of its digits are 4 or 9.

The 3,999 ceiling

Standard Roman numerals stop at 3,999 (MMMCMXCIX), because there's no standard single symbol for 5,000 that this system builds on cleanly — historical extensions exist (a bar over a numeral to multiply it by 1,000) but they're rarely used and not part of the common convention this tool follows.