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Roman numerals still appear all around us — on clock faces, book chapters, movie credits, monarch names and building dates — but reading and writing them isn't obvious once you're past a few letters. This converter turns any number into its Roman form and any valid Roman numeral back into a number, following the strict rules.
Pick the direction, enter your value, and the conversion appears instantly.
How is it calculated?
The seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
The rules
- Symbols are written largest to smallest and added: XVI = 10 + 5 + 1 = 16.
- Subtraction: a smaller symbol before a larger one is subtracted — IV = 4 (not IIII), IX = 9, XL = 40, CM = 900.
- Only I, X and C are used for subtraction, and only before the next one or two sizes up. That's why 4 is IV, never IIII, and 99 is XCIX, not IC.
- The same symbol repeats at most three times (III = 3, but 4 switches to IV).
The range
Standard Roman numerals cover 1 to 3,999. There's no symbol for zero, and numbers above 3,999 need overlines (a bar meaning ×1,000), which this converter doesn't use — so it works within 1–3,999.
Where it helps
- Reading a year in film credits or a cornerstone (MCMXCIV = 1994)
- Writing a chapter, volume or edition number
- Understanding clock faces and monarch/pope names (Louis XIV, Elizabeth II)
Worked example
Convert 2024 to Roman numerals: 2,000 is MM, and 24 is XXIV (X + X + IV, where IV is the subtractive 4), giving MMXXIV. Going the other way, MCMXCIV reads as M (1,000) + CM (900) + XC (90) + IV (4) = 1994 — a common credits-year format. Notice the rules at work: 1994 is not MDCCCCLXXXXIIII; the subtractive forms CM, XC and IV keep it compact. And 4 is always IV, never IIII — a strict rule the converter enforces, rejecting invalid input like IIII.
FAQ
How do I convert a number to Roman numerals?+
Break it into thousands, hundreds, tens and units, and write each with the symbols, using subtraction for 4s and 9s. 2024 = MM + XX + IV = MMXXIV. The tool does it instantly.
How do I read a Roman numeral?+
Add the symbols left to right, but subtract when a smaller one precedes a larger one: MCMXCIV = 1,000 + 900 + 90 + 4 = 1994. Enter it and the tool returns the number.
Why is 4 written IV and not IIII?+
The subtraction rule: a smaller symbol before a larger one is subtracted, so IV = 5 − 1 = 4. A symbol repeats at most three times, so IIII is not valid standard form.
What is the largest Roman numeral?+
In standard notation, 3,999 (MMMCMXCIX). Larger numbers require overlines (a bar for ×1,000), which aren't used here — so this converter covers 1 to 3,999.
Is there a Roman numeral for zero?+
No — the Roman system has no symbol for zero. It represents positive whole numbers only, which is why the converter starts at 1.
What does MCMXCIV mean?+
It's 1994: M (1,000) + CM (900) + XC (90) + IV (4). It's a very common year format in film credits and copyright dates.