Roman Numeral Converter
Convert whole numbers from 1 to 3999 into Roman numerals, or turn Roman numerals like MMXXIV back into numbers.
On this page
A Roman numeral converter flips numbers into Roman numerals and back, and it only needs one box and one button. Choose the direction, type the value, press Convert, and the answer appears right below the input.
Two directions, one box
In Number to Roman mode, 2024 becomes MMXXIV. Flip to Roman to Number, type MMXXIV, and you get 2024 back. Lowercase input works too, so “mmxxiv” converts to 2024 without complaint.
| Number | Roman numeral |
|---|---|
| 4 | IV |
| 9 | IX |
| 40 | XL |
| 90 | XC |
| 400 | CD |
| 900 | CM |
| 2024 | MMXXIV |
| 3999 | MMMCMXCIX |
Those seven pairs are the whole subtraction rule. The tool uses this standard form, so 14 comes back as XIV, never as XIIII.
What gets rejected
Only whole numbers from 1 to 3999 convert. Zero, negative numbers, and anything above 3999 show a validation message, because the classic notation stops there. Roman-form input that breaks convention is rejected too: XIIII, VV, and IC all fail with an explanation rather than returning a guessed value.
Using it
- Pick the conversion direction with the toggle.
- Type the number or numeral.
- Press Convert and read the result under the input.
- Copy it with the icon beside the answer.
If you type in Roman mode and swap the toggle afterward, the tool re-runs the conversion automatically, so you never have to clear and retype to check the other direction.