French Baguette Tools
Roman Numeral Converter
Switch between Arabic numbers and Roman numerals, in both directions. One value per line.
The Roman numeral converter is a free tool that runs entirely in your browser, with no data ever sent to a server. Convert a number to Roman numerals, or the other way around.
How to read a Roman numeral
Seven letters form the base: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. Letters add up when they run from larger to smaller, as in VI for 6. A smaller letter placed before a larger one is subtracted: IV is 4, IX is 9, XC is 90.
Where they are still used
Roman numerals still appear for centuries, regnal and papal numbers, book volumes, clock faces and film credit dates. Converting a production year written in Roman numerals is in fact this tool’s most common use.
What this tool does not do
Classical Roman notation stops at 3999: beyond that it needs overline multipliers that ordinary characters cannot render. Zero and negative numbers do not exist in this system either.
Frequently asked questions
Why is 4 written IV and not IIII?
The subtraction rule avoids repeating the same letter more than three times. So IV rather than IIII, and IX rather than VIIII. Some clock faces still use IIII, purely by aesthetic tradition.
What is the highest possible value?
3999, written MMMCMXCIX. Beyond that, classical notation reaches its limit, since you cannot write more than three M in a row.
Is my data sent to a server?
No: the text you type or paste is processed entirely in your browser, on your device. It is never transmitted to a server.
Do I need an account or an install?
No: the tool works directly on this page, with no sign-up and no installation.