Roman Numeral Converter
Convert numbers to Roman numerals and back, both ways, for 1–3999 — with validation and a quick symbol reference. Free, runs in your browser.
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
💡 How Roman numerals work
- Symbols are added left to right (VI = 6), except when a smaller symbol precedes a larger one, which subtracts (IV = 4, IX = 9).
- Standard Roman numerals represent whole numbers from 1 to 3999 — there is no zero.
- Everything is calculated in your browser.
Free Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers, instantly and both ways. Type in either box and the other updates live, with validation and a quick symbol reference. Supports the standard range 1 to 3999. Free, no sign-up, runs in your browser.
How Roman numerals work
Roman numerals use seven letters — I, V, X, L, C, D, and M — to represent numbers. Symbols are generally written from largest to smallest and added together, so VIII is 8. The exception is subtractive notation: when a smaller symbol comes before a larger one, it is subtracted, which is why IV is 4 and IX is 9. This keeps numerals short and is why you write MCMXCIV rather than a long run of the same letter.
The seven Roman numeral symbols
Each letter has a fixed value:
- I = 1, V = 5, X = 10.
- L = 50, C = 100.
- D = 500, M = 1000.
- Subtractive pairs: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.
How to use the converter
It is fully two-way:
- Type a number (1–3999) to get its Roman numeral.
- Or type a Roman numeral to get its value.
- Invalid input is flagged so you always get a correct result.
- Copy either value with one click.
Why the limit is 3999
Standard Roman numerals only go up to 3999 (MMMCMXCIX). To write 4000 or more you would need four M's in a row, which the classical rules avoid. Larger numbers historically used a bar over a symbol (a vinculum) to multiply it by 1000, but that notation is rarely used today and is not part of the standard set, so this converter sticks to the widely accepted 1–3999 range. There is also no symbol for zero in Roman numerals.
Where Roman numerals are still used
Roman numerals appear in plenty of modern contexts: clock faces, book chapters and page prefixes, movie sequels and copyright years, the Super Bowl, monarch and pope names (Elizabeth II, Louis XIV), and building cornerstones. Being able to convert quickly is handy for reading dates on films and monuments or writing them correctly yourself.
Pro tip
To read a long numeral, scan left to right and watch for a smaller symbol before a larger one — that pair subtracts. To write a year, break it into thousands, hundreds, tens, and ones and convert each part, then join them: 2026 becomes MM + XX + VI = MMXXVI. For converting between number bases like binary and hex, see our Number Base Converter.
FAQ
Is this Roman numeral converter free?
How do I convert a number to a Roman numeral?
How do I convert a Roman numeral to a number?
What is the largest number in standard Roman numerals?
Is there a Roman numeral for zero?
Why is IIII not valid for 4?
How do I write a year like 2026 in Roman numerals?
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