Roman Numeral Converter
Convert a number to Roman numerals or a Roman numeral back to a number — years, film credits, clock faces, monarchs.
Roman numerals add symbols from largest to smallest (I 1, V 5, X 10, L 50, C 100, D 500, M 1000), with the subtractive pairs IV, IX, XL, XC, CD and CM.
How the roman numeral converter works
Roman numerals add symbols from largest to smallest (I 1, V 5, X 10, L 50, C 100, D 500, M 1000), with the subtractive pairs IV, IX, XL, XC, CD and CM. Standard notation covers 1 to 3,999; there is no zero.
Formula: M D C L X V I = 1000 500 100 50 10 5 1; IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900
Worked examples
| Inputs | Result | Note |
|---|---|---|
| 2026 | MMXXVI | MMXXVI |
| 1994 | MCMXCIV | MCMXCIV |
| XLII | 42 | 42 |
FAQFrequently asked questions
Why is 4 written IV and not IIII?
Subtractive notation became standard in the Middle Ages; clock faces often keep IIII for symmetry.
What is the largest standard Roman numeral?
MMMCMXCIX = 3,999. Larger numbers used a bar over the letters to multiply by 1,000.
Is there a Roman numeral for zero?
No — the system had no zero; medieval writers used the word nulla.
How is 2026 written?
MMXXVI: 1000 + 1000 + 10 + 10 + 5 + 1.
Can I write 99 as IC?
Not in standard form; 99 is XCIX. Only I, X and C may be subtracted, and only from the next two larger symbols.
Where these figures come from
- NIST Digital Library of Mathematical Functions — reference definitions for elementary and special functions
- Wolfram MathWorld — definitions and formulas for every topic on this page
- NIST/SEMATECH e-Handbook of Statistical Methods — the statistical formulas (mean, variance, z, confidence intervals, sample size)
- Australian Curriculum (ACARA) — Mathematics — the terms and methods taught in Australian schools
Last checked: September 2026. Formulas are fixed by mathematics and do not change with tax years or regulations.