Roman Numerals

Convert integers from 1 to 3999 into standard Roman numerals, or read a standard numeral back to a number. Subtractive pairs such as IV and CM are included.

Number (1–3999)

Roman

MMXXVI

Standard form up to 3999. Subtractive pairs like IV and CM are included.

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Frequently asked questions

Why is IIII rejected?

Only standard form is accepted. 4 is IV, so a round-trip check rejects IIII.

What is the highest number?

3999, written MMMCMXCIX. Larger numbers need overlines this tool does not use.