Education
Roman Numeral Converter
Two-way converter between ordinary numbers (1–3999) and Roman numerals. Switch direction to spell a number in Roman numerals or decode a Roman numeral back to a number, with strict validation that rejects malformed input like IIII or IC. Runs entirely client-side.
Examples
Input · Uses subtractive notation for 900 (CM) and 90 (XC).
1994
Output
MCMXCIV
How to use Roman Numeral Converter
Pick a direction
Choose Number to Roman or Roman to Number using the toggle.
Enter a value
Type a number from 1 to 3999, or a Roman numeral made of I V X L C D M.
Read the conversion
The converted value appears instantly, with invalid input flagged.
Why use this tool
Converts in both directions
Validates Roman numerals and rejects malformed forms
Covers the full standard range of 1 to 3999
Private and offline — no data is uploaded
Frequently asked questions
Standard Roman numerals only represent values from 1 to 3999 without special overline notation, so the tool enforces that range.
Yes. Non-canonical forms such as IIII, VX or IC are rejected because they do not round-trip to a valid numeral.
Found a bug or have an idea?
ToolOrbit is actively developed — feedback directly shapes what gets built next.
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