Roman Numerals Converter
Convert numbers to Roman numerals and back, for 1 to 3999.
Runs in your browser — nothing is sent or saved.
How to use the Roman numerals converter
- Type a number to get its Roman numeral.
- Or type a Roman numeral to get the number.
- Read the conversion, which detects the direction for you.
- Copy the link to save or share it.
How Roman numerals work
Roman numerals build numbers from seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. You add letters from largest to smallest, so XVI is 10 plus 5 plus 1, which is 16. Where a smaller letter comes before a larger one, you subtract it, so IV is 5 minus 1, which is 4, and IX is 9. This Roman numerals converter applies those rules both directions, so it turns a Roman numeral to number as easily as a number to numeral, and the Roman numerals chart below lists every symbol.
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
The 1 to 3999 range
Standard Roman numerals run from 1 to 3999. There is no symbol for zero, and no standard way to write 4000 or more without special bars over letters, so the converter covers 1 to 3999 and tells you clearly when a number falls outside it. It also rejects invalid numerals: a form like IIII or VX is refused, because the converter checks that the numeral matches the one canonical spelling of its value.
The subtractive rule
Only certain subtractions are allowed, which is what makes 4 into IV rather than IIII. You place I before V or X, X before L or C, and C before D or M, and only one smaller symbol at a time. So 40 is XL, 90 is XC, 900 is CM, and 3999 is MMMCMXCIX. Getting these right is where most by-hand conversions go wrong, and the tool handles them automatically.
A worked example
Take 2024. That is 1000 plus 1000 (MM), then 24, which is 10 plus 10 (XX) plus 4 (IV). So 2024 is MMXXIV. Going the other way, MMXXIV reads as 1000 plus 1000 plus 10 plus 10 plus 4, which is 2024.
FAQ
How do I convert a number to Roman numerals?
Type the number and the converter returns the numeral. For example, 2024 becomes MMXXIV. It works for any whole number from 1 to 3999.
How do I convert Roman numerals to a number?
Type the numeral and the converter returns the number. MCMLXXXIV becomes 1984. It validates the numeral and rejects invalid forms.
Why only up to 3999?
Standard Roman numerals have no symbol beyond M and no zero, so without special notation they stop at 3999 (MMMCMXCIX). The converter enforces that range.
Why is IIII invalid?
Because 4 is written IV using the subtractive rule, not IIII. The converter accepts only the standard canonical spelling of each value.
Is my information private?
Yes. Everything is calculated in your browser and nothing you enter is uploaded or saved.