How to use
- Type a number such as 2026, or Roman numerals such as MMXXVI.
- The conversion appears as you type, in either direction.
- Copy the result.
Options explained
- Subtractive notation
- A smaller symbol before a larger one is subtracted, so IV is 4 and CM is 900. Only I, X and C are used this way, before the next two larger symbols.
- Range
- Standard Roman numerals cover 1 to 3999 (MMMCMXCIX). Larger values need a bar over the letters, which is not part of plain text.
Building a numeral digit by digit
Write the number out by place value and replace each digit with its pattern from the table. 1994 is 1000 + 900 + 90 + 4, which gives M + CM + XC + IV, so MCMXCIV.
| Digit | Thousands | Hundreds | Tens | Units |
|---|---|---|---|---|
| 1 | M | C | X | I |
| 2 | MM | CC | XX | II |
| 3 | MMM | CCC | XXX | III |
| 4 | — | CD | XL | IV |
| 5 | — | D | L | V |
| 6 | — | DC | LX | VI |
| 7 | — | DCC | LXX | VII |
| 8 | — | DCCC | LXXX | VIII |
| 9 | — | CM | XC | IX |
When you type letters, the converter adds up the values, subtracting a symbol that sits before a larger one, and then writes the number back as a numeral. The input is accepted only if that matches what you typed, so IIII, IC, VX and LXXXX are rejected as invalid. Letters can be lowercase. Entering 0 or a number above 3999 shows “Roman numerals go from 1 to 3999.”
Frequently asked questions
Why is IIII rejected when some clocks use it?
IIII appears on clock faces by tradition, but the standard form is IV. The converter accepts only standard numerals so that each number has one spelling.
Is there a Roman numeral for zero?
No. The Romans had no symbol for zero; it was sometimes written as the word nulla.
How do I write a year?
The same way as any number. For example 1999 is MCMXCIX and 2026 is MMXXVI.
Privacy
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