Roman numerals converter
Convert numbers ⇄ Roman numerals.
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Understanding Roman numerals
Roman numerals are a numbering system inherited from ancient Rome, still used today for centuries (21st century), monarch names (Louis XIV), clock faces or chapter numbers. They combine seven letters to represent numbers.
The principle is additive and subtractive: you add the values, except when a smaller symbol precedes a larger one, in which case you subtract it.
How to use the converter
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Enter a number
Type a number from 1 to 3999 to get its Roman form.
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…or a Roman numeral
Type symbols (e.g. MMXXV) to find the decimal value.
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Instant conversion
The two fields are linked: changing one updates the other immediately.
Chart of the seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
All Roman numbers are built from these seven letters.
The subtractive combinations
Six combinations use subtraction: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
Year examples
| Year | Roman numerals |
|---|---|
| 1990 | MCMXC |
| 2000 | MM |
| 2024 | MMXXIV |
| 2025 | MMXXV |
| 1492 | MCDXCII |
| 3999 | MMMCMXCIX |
The writing rules
- Write symbols from largest to smallest, left to right.
- A symbol is not repeated more than three times in a row.
- For 4 and 9 (and their multiples), use subtractive notation.
- Only I, X and C can be subtracted, and only before the two immediately larger symbols.
Frequently asked questions
How do you read Roman numerals?
You add symbols from left to right. When a smaller-value symbol comes before a larger one, you subtract it. Example: VI = 5 + 1 = 6, but IV = 5 − 1 = 4.
Why is 4 written IV and not IIII?
The subtractive rule avoids repeating a symbol more than three times. So 4 is written IV (5−1) and 9 is IX (10−1), rather than IIII or VIIII.
How do I write a year in Roman numerals?
Break it into thousands, hundreds, tens and units, then convert each part. Example: 2025 = 2000 (MM) + 20 (XX) + 5 (V) = MMXXV.
What is the largest number that can be represented?
With the classic symbols, you can reach 3999 (MMMCMXCIX). Beyond that, a multiplication bar (vinculum) is used — not handled here, as it is not standardized.
Is there a zero in Roman numerals?
No. The Roman system has no symbol for zero, nor for negative or decimal numbers: it is for counting positive whole quantities.
Is my data sent online?
No. The conversion happens in your browser, with no data sent anywhere.