Roman Numeral Converter
Numbers ⇄ Roman numerals, 1 to 3999.
How to use
- 1 Type a number from 1 to 3999 in the first field to see its Roman numeral.
- 2 Type a Roman numeral in the second field to convert it back to a number.
- 3 Read the result, which updates as you type.
- 4 Copy whichever value you need.
About Roman Numeral Converter
The Roman Numeral Converter turns ordinary numbers into Roman numerals and reads numerals back into numbers.
Enter a value between 1 and 3999 to get its canonical numeral — 1994 becomes MCMXCIV — or type a numeral to recover the integer it represents.
Roman numerals still appear on clock faces, book chapters, film copyright dates, monuments and the Super Bowl, but the rules are fiddly: subtractive pairs like IV and IX, no symbol repeated more than three times, and a fixed ordering of M, D, C, L, X, V and I.
This tool encodes those rules properly.
When you convert a numeral to a number it does not just add up the letters; it round-trips the result and rejects anything that is not in strict canonical form, so common mistakes such as IIII, VV or IC are flagged rather than silently accepted.
Conversion happens instantly as you type, with a clear error message when a value falls outside the 1–3999 range that classical Roman numerals can express.
Everything runs client-side: no network request, no tracking, and it works offline.
Whether you are dating an inscription, numbering an outline or just settling a pub argument, you get an answer you can trust in a fraction of a second.
FAQ
Why is the range limited to 1–3999?
Standard Roman numerals only use the symbols up to M (1000); 3999 is the largest value expressible without overlines or other extensions.
Does it accept lowercase numerals?
Yes. Input is case-insensitive, so mcmxciv and MCMXCIV both work.
Will it accept IIII for 4?
No. The converter enforces canonical form, so 4 must be written IV. Non-standard numerals are rejected with an error.