Roman Numeral Converter
Numbers โ Roman numerals.
Roman Numeral Converter at a glance
Roman Numeral Converter is a free online converter you can use right now to numbers โ Roman numerals โ no account, no install and no usage limit. It runs entirely inside your browser, so whatever you enter stays on your own device.
- Price
- Free โ no trial, no paid tier, no watermark
- Sign-up
- Not required
- Where it runs
- In your browser โ nothing is uploaded to a server
- Works on
- Chrome, Safari, Firefox and Edge โ desktop, tablet and phone
- Category
- Converters
About Roman Numeral Converter
Convert an ordinary number into Roman numerals or read a Roman numeral back as a number.
The system uses seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. Values are generally added left to right, so XVI is 16. The exception is subtractive notation: when a smaller value precedes a larger one it is subtracted, so IV is 4 and IX is 9. This is why 1994 is MCMXCIV โ M for 1000, CM for 900, XC for 90 and IV for 4.
Subtractive notation follows rules that are commonly broken in casual use. Only I, X and C may be subtracted, and only from the next two larger values โ so IV and IX are valid, IL and IC are not. This is why 49 is XLIX rather than IL, which trips people up because IL looks reasonable.
The system has real limits: there is no zero and no way to write negative or fractional numbers, and standard notation stops at 3999 because representing 4000 would need four Ms. These constraints are exactly why positional systems with a zero replaced it for arithmetic. Roman numerals survive for clock faces, book chapters, film copyright dates, monarch numbering and Super Bowl editions.
How to use Roman Numeral Converter
- Enter a number, or a Roman numeral.
- The conversion appears instantly in the other direction.
- Check subtractive pairs such as IV, IX, XL and CM if a numeral looks unfamiliar.
Frequently asked questions
Why is 4 written IV rather than IIII?
Because of subtractive notation โ a smaller value before a larger one is subtracted. IIII does appear historically and still on some clock faces, but IV is the standard modern form.
Why is 49 XLIX and not IL?
Only I, X and C may be subtracted, and only from the next two larger values. IL is not valid, so 49 is built as XL (40) plus IX (9).
What is the largest number I can write?
3999 in standard notation, since 4000 would require four Ms. Larger numbers historically used a bar above a numeral to multiply it by 1000, but that is not part of standard modern usage.
How do I write zero?
You cannot. The system has no zero and no negative or fractional numbers, which is precisely why positional systems replaced it for arithmetic.