Roman Numeral Converter
Convert numbers to Roman numerals and back, with strict validation of the notation.
Your result will appear here as soon as you add some input.
How to use it
- 1Enter your values in the fields above.
- 2The answer and the working appear immediately below.
- 3Check the working to see the formula with your numbers substituted.
Example
Input
2026
Output
MMXXVI
About the Roman Numeral Converter
The standard system covers 1 to 3,999. There is no numeral for zero, none for negatives, and values above 3,999 need overlines that plain text cannot represent.
Subtractive notation is restricted: only I, X and C may be placed before a larger numeral, and only before the next two values up. That is why 99 is XCIX and not IC - and why non-standard forms are rejected here with the correct version shown.
Questions people ask
Is your figures uploaded to a server?
No. This tool runs entirely in your browser using standard web APIs, so your figures never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.
Is it free, and do I need an account?
Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.