Convert decimal numbers to Roman numerals and Roman numerals back to decimal instantly.
Roman Numeral Converter
Decimal ↔ Roman numeral
Supports integers from 1 to 3,999. Enter a value in either field and choose the corresponding conversion.
How to use the converter
For decimal to Roman, enter an integer from 1 to 3,999. For Roman to decimal, use only I, V, X, L, C, D and M in canonical order.
What are Roman numerals?
Roman numerals are a number system from ancient Rome. They combine seven symbols: I, V, X, L, C, D and M.
Formation rules
Symbols are usually added from left to right. A smaller symbol before a larger one is subtracted, as in IV = 4 and IX = 9. I, X, C and M may repeat up to three times.
Conversion examples
| Decimal | Roman numeral |
|---|---|
| 1 | I |
| 4 | IV |
| 9 | IX |
| 49 | XLIX |
| 2024 | MMXXIV |
| 3999 | MMMCMXCIX |
Frequently asked questions
How do I convert a decimal number to Roman numerals?
Break the number into thousands, hundreds, tens and units, then replace each part with the corresponding Roman symbols.
Which Roman numeral symbols are used?
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000.
Why is 4 written IV instead of IIII?
A smaller numeral before a larger numeral indicates subtraction, so IV means 5 − 1.
What range does the converter support?
It supports canonical Roman numerals from 1 to 3,999.
Are lowercase letters accepted?
Yes. Lowercase input is automatically converted to uppercase.
See also…
