Toolstia / Roman numeral converter
Roman numeral converter
Turn a number from 1 to 3999 into a Roman numeral, or read a Roman numeral as a number. Invalid numerals are rejected with a clear message.
| Number | Roman |
|---|---|
| 4 | IV |
| 9 | IX |
| 14 | XIV |
| 40 | XL |
| 90 | XC |
| 400 | CD |
| 1994 | MCMXCIV |
| 2026 | MMXXVI |
How it works
- Choose the direction.
- Type the number or the Roman numeral.
- Copy the result.
The letters
I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. Smaller letters before a larger one are subtracted, so IV is 4 and CM is 900.
Why 3999 is the limit
The standard system has no symbol above M and does not repeat a letter more than three times in a row, so the largest number written in the standard form is MMMCMXCIX, which is 3999.
Strict checking
The tool only accepts numerals written in the standard way. IIII and IC are rejected, because the standard forms are IV and XCIX.
Common uses
Roman numerals appear on clocks, in book chapters, film and event numbering, and in the names of monarchs.
Questions
Is there a Roman zero?
No. The system has no zero.
Does it accept lowercase?
Yes. mcmxciv works as well as MCMXCIV.
What about numbers above 3999?
They have no standard form, so the tool asks for a smaller number.
Is it free?
Yes, and it works offline in your browser.