Roman Numerals

How to use it

1. Type a Roman numeral like MCMXCIV or a whole number between 1 and 3999 into the input field.
2. Click Roman -> Number to translate a numeral into a value, or Number -> Roman to go the other way.
3. Read the result below the buttons. Invalid input shows a clear error message instead of a wrong answer.
4. Press Sample to load a working example, or Clear to start over.

Common use cases

• Reading clock faces and monuments - film credits, book chapters and building cornerstones often use Roman numerals, and clock faces traditionally write IIII, which this tool accepts.
• Sorting outlines and drafts - turn section numbers such as IV, IX or XL into values you can sort and compute with.
• Checking homework - verify a hand-written conversion before submitting it.
• Converting years - switch between MMXXVI and 2026 in either direction.

Why it stays private

Conversion runs entirely in your browser's memory. Nothing is uploaded, there is no account, and no network request is made, so whatever numeral you paste never leaves your device.

FAQ

Q: Is IIII a valid input? A: Yes. IIII is the traditional clock-face form of 4 and is accepted alongside IV. Output always uses the standard subtractive form, so 4 comes back as IV.

Q: Why is my number rejected? A: The converter covers 1-3999, the classic Roman range without the vinculum (overbar) notation. Larger numbers need that notation and are out of scope.

Q: Are lowercase numerals like mcmxciv accepted? A: Yes. Input is case-insensitive: MCMXCIV and mcmxciv both convert to 1994.