About Roman Numeral Converter

Roman Numeral Converter moves a value between three forms: a plain number, a Roman numeral, and the English words for the number.

It runs in the page. Roman numerals use the standard form and cover 1 to 3999.

How to use it

  1. Type a value into any of the three boxes.
  2. The other two boxes update as you type.
  3. Copy whichever form you need.

Common questions

Why does it stop at 3999?

Standard Roman numerals have no single symbol above M. Larger values need a bar notation that is rarely used, so this tool keeps to 1 to 3999.

Does it accept lowercase Roman numerals?

Yes. Input is case-insensitive. It still checks that the numeral is well formed, so IIII is rejected.

How large a number can it spell out?

Into the quintillions. Very large values are refused rather than named loosely.

Is anything uploaded?

No. The conversion is a small local calculation.