Roman Numerals Converter
Type a whole number from 1 to 3999 to get its Roman numeral, or switch direction and type a numeral such as MCMXCIV to get the number. You see the breakdown into parts, a symbol reference and the steps. Invalid numerals are rejected with the rule they break.
Last updated November 4, 2026
A whole number from 1 to 3999.
Result
1994 = MCMXCIV
| Part | Value |
|---|---|
| M | 1000 |
| CM | 900 |
| XC | 90 |
| IV | 4 |
| I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|
| 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
Show the work
Formula: Write the largest values first; a smaller symbol before a larger one is subtracted (IV = 5 - 1)
- Start with 1994. Take the largest value from the table (M 1000, CM 900, D 500, CD 400, C 100, XC 90, L 50, XL 40, X 10, IX 9, V 5, IV 4, I 1) that fits, subtract it, and repeat.
- Parts: M 1000 + CM 900 + XC 90 + IV 4.
- Add the parts to check: 1000 + 900 + 90 + 4 = 1994.
- Write the symbols in order: MCMXCIV.
Result: 1994 = MCMXCIV
How Roman numerals are built
number = sum of the symbol values, where a smaller symbol written before a larger one is subtracted (IV = 5 - 1 = 4)
Roman numerals use seven symbols: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. Symbols are normally written from largest to smallest and their values are added, so XVI is 10 + 5 + 1 = 16.
To write a number, take the largest value from the table that still fits, write its symbol, subtract the value and repeat. The table has thirteen entries: the seven symbols plus the six subtractive pairs IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
To read a numeral, go left to right. When a symbol is smaller than the one after it, subtract it; otherwise add it. In MCMXCIV the C before M and the X before C and the I before V are subtracted: 1000 + (1000 - 100) + (100 - 10) + (5 - 1) = 1994.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Also useful alongside this calculator: Binary Converter, Basic Calculator and Factor Calculator.
The subtractive rule and its limits
Only six subtractive pairs are standard. I may come before V or X, X before L or C, and C before D or M. V, L and D are never subtracted, so VX, LC and DM are invalid. IC for 99 and XM for 990 are invalid too. Write 99 as XCIX and 990 as CMXC.
Ancient inscriptions sometimes show IIII for 4, and many clock faces still do. Modern standard notation uses IV, and this converter accepts only that form so every number has exactly one numeral.
How often a symbol can repeat
I, X, C and M may repeat up to three times in a row: III is 3, XXX is 30, CCC is 300 and MMM is 3000. A fourth repetition is replaced by a subtractive pair, so 4 is IV, 40 is XL and 400 is CD.
V, L and D never repeat, because two of them would be written as the next larger symbol: VV is X, LL is C and DD is M.
Zero, negatives and numbers above 3999
The Romans had no symbol for zero and no way to write negative numbers or decimals in this system, so the converter rejects 0, negatives and fractions with a message.
The largest number in standard notation is 3999, written MMMCMXCIX, because M cannot repeat more than three times. Larger values were written in historic practice with a bar (vinculum) over a numeral to multiply it by 1000. That extension exists, but it is not supported here.
Where Roman numerals are still used
You will meet Roman numerals in book chapters and prefaces, outlines, clock faces, film and game copyright years, monarch and pope names such as Elizabeth II, and event numbering such as the Super Bowl. Copyright years are a handy test: 2024 is MMXXIV.
How to use the Roman Numerals Converter
- Choose Number to Roman numeral or Roman numeral to number.
- Type a whole number from 1 to 3999, or a numeral using I, V, X, L, C, D and M in any case.
- Read the result and the table showing each part with its value.
- Open Show the work to see how the parts add up to the number.
- Use Copy, Print or Share to keep the result.
Worked example
Convert 1994. The largest value that fits is M (1000), leaving 994. Next CM (900) leaves 94, then XC (90) leaves 4, then IV (4). The numeral is MCMXCIV. Check: 1000 + 900 + 90 + 4 = 1994.
| Number | Roman numeral | Parts |
|---|---|---|
| 4 | IV | IV 4 |
| 14 | XIV | X 10 + IV 4 |
| 90 | XC | XC 90 |
| 1994 | MCMXCIV | M 1000 + CM 900 + XC 90 + IV 4 |
| 2024 | MMXXIV | M 1000 + M 1000 + X 10 + X 10 + IV 4 |
| 3999 | MMMCMXCIX | M 1000 + M 1000 + M 1000 + CM 900 + XC 90 + IX 9 |
Frequently asked questions
Is there a Roman numeral for zero?
No. The Romans had no symbol for zero in their numerals, so this converter rejects 0 and only accepts numbers from 1 to 3999.
Why is 4 written IV and not IIII?
Standard notation allows a symbol to repeat only three times in a row, so 4 becomes IV, which is 5 minus 1. IIII appears on some clock faces but is rejected here.
What is the largest Roman numeral this converter accepts?
It accepts up to 3999, written MMMCMXCIX. Bigger numbers need the overline (vinculum) extension, which is not supported.
Why does the converter reject VX or IC?
Only IV, IX, XL, XC, CD and CM are valid subtractive pairs. V cannot be subtracted, and I may only precede V or X, so 99 is XCIX, not IC.
Can I type a Roman numeral in lowercase?
Yes. Letters in any case are accepted and outer spaces are ignored, so mmxxiv is read as MMXXIV, which is 2024.