Roman Numeral Converter
WEBConvert numbers to Roman numerals and Roman numerals back to numbers instantly, free and online for the 1-3999 range.
Enter a whole number from 1 to 3999.
Nothing to convert yet
Type a number or a Roman numeral above to see the conversion.
What is the Roman Numeral Converter tool?
This Roman numeral converter works both ways: type a whole number and get its Roman numeral, or type a Roman numeral and get the number it represents. Switch direction with a single tap, and the result updates as you type — no separate 'convert' button to press.
It covers the full classical range of 1 to 3999, the span every standard Roman numeral system can represent with the symbols I, V, X, L, C, D and M. Numbers outside that range, and malformed Roman numerals such as repeated symbols past their limit or an invalid subtractive pair, are flagged immediately with a clear message instead of a silent wrong answer.
Roman numerals still show up everywhere: movie sequel titles and copyright years, clock faces, book chapter and volume numbers, outline headings, monarch and Super Bowl numbering, and tattoo dates. This tool is built for exactly those quick lookups — figure out what year 'MMXXIV' represents, double-check a numeral before it goes on a wedding invitation, or turn a birth year into a numeral design in seconds, right in your browser, with nothing to install.
How to use the Roman Numeral Converter
- Choose a direction: 'Number to Roman' or 'Roman to number'.
- Type your number (1–3999) or your Roman numeral into the field.
- Read the converted result as it updates instantly.
- If the input is out of range or malformed, an inline message tells you why.
- Copy or share the result straight from the result card.
Frequently asked questions
What is the highest number this converter supports?
3999 (MMMCMXCIX), the largest value the standard Roman numeral symbols I, V, X, L, C, D and M can represent without extended notation. Numbers of 4000 or more, and 0 or below, are flagged as out of range.
Why does the tool reject numerals like 'IIII' or 'VV'?
Because those aren't valid Roman numerals under the standard rules — a symbol can only repeat up to three times in a row (III, not IIII), and symbols like V, L and D never repeat at all. The converter validates strictly so you always get either a correct answer or a clear reason it couldn't convert.
Does it matter if I type Roman numerals in lowercase?
No — lowercase input like 'mcmxciv' is automatically read as uppercase and converted normally. Only the underlying letters and their arrangement need to be a valid Roman numeral.
Can I convert a Roman numeral back to check my work?
Yes. Switch to 'Roman to number' mode, paste or type the numeral, and you'll see the number it represents — handy for double-checking a numeral before using it somewhere permanent, like an engraving or a document.
Is this Roman numeral converter free to use?
Yes — completely free, with no sign-up, no account and no limits. It also works entirely in your browser, so nothing you type is sent anywhere.