Roman Numeral Converter
Convert numbers (1–3999) to Roman numerals and Roman numerals back to numbers. Handy for outlines, chapter numbers, front-matter page numbers, and dates.
Direction
Roman Numeral Reference
| Number | Roman numeral |
|---|---|
| 1 | I |
| 4 | IV |
| 5 | V |
| 9 | IX |
| 10 | X |
| 40 | XL |
| 50 | L |
| 90 | XC |
| 100 | C |
| 400 | CD |
| 500 | D |
| 900 | CM |
| 1000 | M |
| 2026 (this year) | MMXXVI |
Frequently Asked Questions
- How do I convert a number to Roman numerals?
- Type any whole number from 1 to 3999 into the input box. The tool detects that it is a number and instantly shows the Roman numeral, which you can copy with one click.
- Why is the range limited to 1-3999?
- Standard Roman numerals have no symbol larger than M (1000), and a symbol may repeat at most three times. That makes MMMCMXCIX (3999) the largest number writable in the standard notation. There is also no Roman numeral for zero.
- Does the tool reject invalid Roman numerals?
- Yes. After parsing your input, the tool re-encodes the value and compares it with what you typed. Malformed sequences like IIII, VX, or IC are flagged as invalid instead of being silently accepted.
- Where are Roman numerals used in academic writing?
- They number front-matter pages (i, ii, iii), outline levels, book volumes and parts, monarchs and popes (Elizabeth II), sequels, and centuries in some styles. Chicago and MLA both use lowercase Roman numerals when citing front-matter page numbers.
- What is subtractive notation?
- Placing a smaller symbol before a larger one subtracts it: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400, and CM is 900. Only these six subtractive pairs are valid in standard Roman numerals.