Roman Numeral Converter
Convert between Arabic and Roman numerals — both directions, any number from 1 to 3999. Useful for movie titles, watch faces, document numbering, and classics.
Reference: common Roman numerals
| Arabic | Roman | Arabic | Roman |
|---|---|---|---|
| 1 | I | 50 | L |
| 2 | II | 100 | C |
| 3 | III | 500 | D |
| 4 | IV | 1000 | M |
| 5 | V | 1900 | MCM |
| 9 | IX | 1999 | MCMXCIX |
| 10 | X | 2025 | MMXXV |
| 40 | XL | 3999 | MMMCMXCIX |
How to Use
Type an Arabic number (1–3999) or a Roman numeral (I, V, X, L, C, D, M). The other field updates automatically.
Out-of-range or invalid input is flagged in red. Output uses standard subtractive notation (IV=4, IX=9, XL=40, etc.).
One-click copy. The reference table below shows common Arabic ↔ Roman mappings.
FAQ
Why only up to 3999?
Standard Roman numerals are defined for 1–3999. Larger values use the "vinculum" (a bar over the letter to mean ×1000) but there's no consistent ASCII representation, so this tool stops at 3999.
Can I represent 0?
There is no Roman numeral for zero — the concept itself entered Western math much later through Indian-Arabic numerals.
IIII vs IV?
The standard form is IV (subtractive). The tool always outputs IV / IX / XL / XC / CD / CM. IIII is a watchmaking convention; the tool still accepts it as 4 when parsing Roman → Arabic.
Lowercase OK?
Yes — input accepts any case; output is always uppercase (M, D, C, L, X, V, I) per convention.
Is anything sent to a server?
No. Everything runs in your browser; nothing leaves the page.
