Roman Numeral Converter

About Roman numeral converter

Converts whole numbers from 1 to 3999 into Roman numerals and Roman numerals back into numbers. It only accepts standard subtractive notation, and a breakdown table shows exactly which chunks add up to the answer, which makes it good for learning as well as for quick lookups.

How to use it

1. Choose a Direction: Number to Roman or Roman to number.
2. Type a value into the Number field, or a numeral into the Roman numeral field.
3. Read the result, and study the How it decomposes table with its running total.
4. Try the shortcut buttons (4, 9, 14, 40, 49, 1987, 2026, 3999) or press Swap to move the result into the other field.

A famous year

1994

MCMXCIV, made of M (1000) + CM (900) + XC (90) + IV (4)

When to use it

• Writing the year on a monument, diploma or building inscription.
• Numbering chapters, appendices or film sequels in Roman style.
• Reading the copyright year at the end of an old movie's credits.
• Marking outline levels or clock faces with correct numerals.

Questions about Roman numeral converter

Why is 4000 refused?

The standard system tops out at 3999, MMMCMXCIX, because it has no symbol for 5000 and repeats M at most three times. Larger values need overlines, which this tool does not support.

Why is IIII rejected when it appears on clocks?

Clock faces use it by tradition, but standard notation writes 4 as IV. The tool reports the standard form, for example that IC should be XCIX.

Does lowercase work?

Yes. Input is converted to capitals before it is checked, and the field displays capitals as you type.

Can I convert 0 or a decimal?

No. Romans had no symbol for zero and no fractions in this notation, so only whole numbers between 1 and 3999 are accepted.

What counts as valid?

Only the canonical spelling of a value. Something like VX or IL would give a naive parser a number but is not legitimate notation, so the tool refuses it.

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