How Roman numerals work
Seven letters carry the values I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Write each place value from largest to smallest and add them up: 2026 = MM + XX + VI = MMXXVI. When a smaller symbol comes before a larger one it is subtracted, which gives the six standard pairs IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
What counts as standard?
In the standard form a symbol repeats at most three times, and only I, X and C are placed in front to subtract. You will still see IIII on clock faces and forms like IC for 99; this converter reads them and shows the standard spelling next to the result. The largest standard number is 3999 (MMMCMXCIX); larger values used a bar over the letters, which is outside this tool.
Tips
- Lowercase letters and Unicode numerals such as Ⅻ are accepted.
- There is no Roman numeral for zero or for negative numbers.
Is anything sent to a server?
No. Everything runs in your browser. Nothing you enter is uploaded; settings you change are only remembered on this device.