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
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Enter the values
Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.
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Instant answer
The answer appears as you type, with the most important intermediate values.
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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.
Frequently asked questions
Is the roman numerals free?
Yes. The roman numerals is completely free, with no account, sign-up or usage limit.
How accurate is the result?
The tool calculates with your browser's number precision. For important calculations, always double-check what you entered.
Does it work on my phone?
Yes. The tool works in any modern browser on a phone, tablet or computer.