Roman Numeral Converter
Type a number to get its Roman numeral, or type a Roman numeral to get the number, with a breakdown of how it is built.
How to convert Roman numerals
- To get a Roman numeral, type a whole number from 1 to 3999 in the first box.
- To go the other way, type a numeral such as MCMXCIV in the second box.
- The breakdown shows which symbols add up to the total.
Features
Both directions
Numbers to numerals and numerals to numbers.
Step-by-step breakdown
See each symbol and its value.
Strict validation
Rejects malformed numerals like IIII or VX.
Private
Conversion runs in your browser; nothing is uploaded.
Frequently asked questions
How do Roman numerals work?
Seven letters carry values: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. Symbols are added from largest to smallest, and a smaller symbol placed before a larger one is subtracted, so IV is 4 and XC is 90.
Why is the maximum 3999?
Standard Roman numerals have no symbol above M (1000) and a symbol repeats at most three times, so 3999 (MMMCMXCIX) is the largest. Larger values historically used a bar over the numeral to multiply by 1000.
What are the subtractive pairs?
Only six pairs are valid: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). Others such as IC for 99 are not standard; 99 is XCIX.
Is there a zero in Roman numerals?
No. The Romans had no symbol for zero, so the converter starts at 1.