Numerals
Roman Numeral Converter
Convert numbers to Roman numerals and back, for 1 to 3999. Type in either field and see the symbol breakdown update instantly.
How to use the Roman numeral converter
This Roman numeral converter works in both directions. Type an ordinary number into the top box to see its Roman form, or type a Roman numeral into the bottom box to read off the modern value. The breakdown chips show exactly how the result is built — for example 2025 becomes MM (2000) + XX (20) + V (5), written MMXXV.
Roman numerals use seven letters, each standing for a fixed value. Larger symbols come first; a smaller symbol placed before a larger one is subtracted (so IV is 4, not 6).
Roman numeral chart
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
Why the limit is 1 to 3999
Standard Roman numerals only run from 1 to 3999. There is no symbol for zero, and the largest single letter is M (1000) — so the biggest number you can write with the basic set is MMMCMXCIX (3999). Numbers above that historically used a bar over a letter (a vinculum) to multiply it by 1000, but that notation is rarely needed today. Enter anything outside the 1–3999 range and the converter flags it in amber rather than guessing.
Frequently asked questions
How do you write 2025 in Roman numerals?
2025 is MMXXV — that is MM (2000) + XX (20) + V (5). Type 2025 in the Number box above to see the full breakdown.
What is the largest number in Roman numerals?
Using the standard symbols, the largest value is 3999, written MMMCMXCIX. There is no symbol for zero or for numbers above 3999 in the basic system.
Why is 4 written as IV and not IIII?
Roman numerals use subtractive notation: a smaller symbol before a larger one is subtracted. So IV means 5 − 1 = 4. The same rule gives IX (9), XL (40) and CM (900).
Can I convert a Roman numeral back to a number?
Yes. Type the Roman numeral into the lower box and the matching number appears above. Invalid letters are stripped and the note turns amber if the result is not valid.
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