Roman Numeral Converter
Type a number or type Roman numerals — the page works out which you meant and converts it, showing the sum it used. Nothing is uploaded.
| Symbol | Value | Note |
|---|---|---|
| I | 1 | |
| IV | 4 | one before five |
| V | 5 | |
| IX | 9 | one before ten |
| X | 10 | |
| XL | 40 | ten before fifty |
| L | 50 | |
| XC | 90 | ten before a hundred |
| C | 100 | |
| CD | 400 | hundred before five hundred |
| D | 500 | |
| CM | 900 | hundred before a thousand |
| M | 1000 | the largest single letter |
Only I, X and C are ever subtracted, and only from the next two values up. That is why 99 is XCIX and never IC.
How to use it
- Type a number, such as 2026, or Roman numerals, such as MMXXVI.
- The page works out which one you typed — no switch to flip.
- The line under the tiles shows the sum, so you can check it rather than trust it.
The rule that explains almost everything
A Roman numeral is read left to right, adding as you go, with one exception: a smaller symbol in front of a larger one is subtracted instead. So VI is 5 + 1 = 6, but IV is 5 − 1 = 4. Once you have that, MCMXCIV comes apart cleanly: M is 1000, CM is 900, XC is 90, IV is 4, and they add to 1994.
The subtraction is not allowed everywhere. Only I, X and C are ever put in front, and only in front of the next two values up. That gives exactly six legal pairs — IV, IX, XL, XC, CD, CM — and no others. IC for 99 looks sensible and is wrong; the answer is XCIX.
Why it stops at 3999
M is the largest letter, and no letter may repeat more than three times, so MMM is 3000 and there is nothing left to add for 4000. The Romans handled bigger numbers by drawing a bar over a letter to multiply it by a thousand. That bar is a mark on top of a character rather than a character of its own, so it does not survive being copied, pasted or typed into a form. Rather than invent a spelling nobody else uses, this converter stops where the letters stop and says so.
Where you still meet them
Copyright years at the end of films, chapter and appendix numbers, Super Bowls, monarchs and popes, the faces of expensive clocks, and the outline of almost every formal document. Reading a film's closing MMXIV is the single most common reason people look one of these up.
Clock faces are the famous exception to the rules above. Many print IIII rather than IV for four, because IIII balances the VIII directly opposite it and because it keeps the first four hours using only I. It is a design choice, not a spelling, and this page will flag it.
Frequently asked questions
Why is 4 written IV and not IIII?
Because a smaller symbol placed before a larger one is subtracted from it, so IV is five minus one. The rule keeps any symbol from repeating more than three times in a row. IIII does appear on clock faces, where it balances the VIII opposite it, but it is not the standard spelling and this converter will tell you so.
What is the largest Roman numeral?
With the ordinary seven letters it is MMMCMXCIX, which is 3999. There is no single letter for 5000, and M can only repeat three times, so 4000 cannot be spelled. Larger numbers needed a bar drawn over a letter to multiply it by a thousand, which is a mark rather than a character and does not survive being copied as plain text.
Is there a Roman numeral for zero?
No. The system counts things, and it was built before zero was treated as a number in Europe. There is no symbol for it and no way to write a negative number or a fraction of one either, which is why this converter starts at 1.
Is anything I type sent anywhere?
No. The conversion happens in JavaScript inside your own browser. Nothing is uploaded and nothing is saved - close the tab and it is gone.