Roman Numeral Converter
Convert numbers to Roman numerals and back again, from 1 to 3999. Type in either box and the other updates instantly.
Numbers and Roman numerals, both ways
Roman numerals still turn up everywhere — clock faces, book chapters, movie copyright years, Super Bowl numbers and monarch names. This converter handles both directions: enter a number to see its numeral, or paste a numeral to read the value. It validates as it goes, so you can trust the result for tattoos, dates and homework alike.
The seven symbols
Every Roman numeral is built from seven letters: I (1),
V (5), X (10), L (50),
C (100), D (500) and M (1000).
Symbols are written from largest to smallest and added up. The exception
is the subtractive pairs — IV (4), IX (9),
XL (40), XC (90), CD (400) and
CM (900) — where a smaller symbol before a larger one means
subtract.
Tips
- Years are easy: 2024 becomes
MMXXIV. - No zero: Roman numerals have no symbol for nothing, so the lowest value is 1.
- Stay under 4000: standard notation tops out at 3999 (
MMMCMXCIX).
Frequently asked questions
What range of numbers is supported?
Standard Roman numerals run from 1 (I) to 3999 (MMMCMXCIX). There is no symbol for zero or for negative numbers, and values above 3999 require overlines that aren't part of basic notation, so the converter accepts whole numbers from 1 to 3999.
How do Roman numerals work?
Seven letters carry value: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. They're written largest to smallest and added together, except when a smaller letter sits before a larger one (IV = 4, IX = 9, XL = 40), which means subtract.
Why does it reject something like IIII or VX?
Those aren't valid in standard notation. A letter can repeat at most three times (so 4 is IV, not IIII) and only specific subtractive pairs are allowed. The converter validates the numeral and shows a message instead of guessing.
Is my input sent anywhere?
No. The conversion is plain arithmetic that runs entirely in your browser. Nothing is uploaded.