Standard Roman numerals: 1 to 3999 (I to MMMCMXCIX). Values above 4000 would require overline notation which is not commonly used.

How do Roman numerals work?

Basic symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Smaller values before larger ones subtract (IV=4, IX=9, XC=90).

Why is there no zero?

The Roman numeral system has no concept of zero or negative numbers - it represents counting only positive whole numbers.

No. Inputs like IIII (for 4) or VX (for 5) are rejected. The result must round-trip back to the canonical form to be valid.

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What is the range?: Standard Roman numerals: 1 to 3999 (I to MMMCMXCIX). Values above 4000 would require overline notation which is not commonly used.
How do Roman numerals work?: Basic symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Smaller values before larger ones subtract (IV=4, IX=9, XC=90).
Why is there no zero?: The Roman numeral system has no concept of zero or negative numbers - it represents counting only positive whole numbers.
Does the tool accept non-canonical input?: No. Inputs like IIII (for 4) or VX (for 5) are rejected. The result must round-trip back to the canonical form to be valid.