Roman numeral converter
Type a number to see it in Roman numerals, or type Roman numerals such as MMXXVI to see the number. The tool detects which way you want to go and shows how it is built up.
A number from 1 to 3999 becomes Roman; Roman numerals (upper or lower case) become a number.
Fill in the fields; the answer appears here straight away.
How it's worked out
How it works
-
Enter the values
Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.
-
Instant answer
The answer appears as you type, with the most important intermediate values.
-
See the working
Under "How it's worked out" you see the steps, handy for checking your own calculation.
The seven Roman numerals
| I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|
| 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
You add the values from large to small: MDCLXVI = 1000 + 500 + 100 + 50 + 10 + 5 + 1 = 1666.
Subtraction: IV, IX, XL, XC, CD and CM
When a smaller numeral stands before a larger one, you subtract it. That only happens in six fixed pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). So 1994 is MCMXCIV: M (1000) + CM (900) + XC (90) + IV (4). The same numeral never appears more than three times in a row, so 4 is IV and not IIII (although you do see IIII on some clocks). If you type such a non-standard form, you get its value and the standard way to write it.
Why stop at 3999?
With the normal letters, MMMCMXCIX (3999) is the largest number. For larger numbers the Romans drew a line above the letters (times 1000), but that notation isn't consistent and can't be typed easily. The Romans had no numeral for 0.
Examples worth knowing
| Number | Roman numeral | Why |
|---|---|---|
| 4 | IV | 5 − 1 |
| 9 | IX | 10 − 1 |
| 49 | XLIX | XL (40) + IX (9) |
| 99 | XCIX | XC (90) + IX (9) |
| 1994 | MCMXCIV | M + CM + XC + IV |
| 2026 | MMXXVI | MM + XX + VI |
Why 49 is not IL
You subtract only in the six fixed pairs, and only a power of ten (I, X, C) before the next two larger numerals. So 49 is XLIX and 99 is XCIX, never IL or IC.
Where you still see them
On clock faces, in chapter and film sequel numbers, in the copyright year in old films, for kings and popes (Elizabeth II, John Paul II), and for the numbering of sports events such as the Super Bowl. For other number systems, see the number base converter, and for the gap between two dates, days between dates.
Frequently asked questions
How do I write 2026 in Roman numerals?
MMXXVI: MM is 2000, XX is 20 and VI is 6. Type 2026 into the converter to see it built up.
What is the largest number you can write?
3,999, which is MMMCMXCIX. Beyond that you would need a fifth repeated M or an overline notation that has no standard typed form.
Is there a Roman numeral for zero?
No. The Romans had no digit for zero, so the converter works from 1.
Can I type lowercase Roman numerals?
Yes. Both capitals and small letters are read, so mmxxvi and MMXXVI give 2026.