Roman Numeral Converter — Free Online Tool
Convert any integer from 1 to 3,999 to its Roman numeral representation, or convert a Roman numeral string back to an integer. The tool auto-detects which direction to convert based on the input. Invalid Roman numeral strings are flagged with an error message.
100% client-side. No uploads. Your data never leaves your browser.
How to use Roman Numeral Converter
- Type a number (1–3,999) or a Roman numeral string into the input.
- The tool auto-detects whether to convert to or from Roman numerals.
- The result appears instantly below.
- Copy the result with the Copy button.
Frequently Asked Questions
Why is the maximum value 3,999?
Standard Roman numerals cannot represent 4,000 or above without special extensions (like a bar over a letter to mean ×1000). The tool uses the standard 7-symbol system.
Is IIII valid or should it be IV?
IV is the subtractive notation used in standard Roman numerals. IIII is sometimes seen on clock faces but is non-standard. This tool uses subtractive notation.
Can I convert zero?
Romans had no numeral for zero. The tool returns an error for zero input.
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