How do you read a Roman numeral?

Read from left to right and add each value, but when a smaller symbol comes before a larger one, subtract it: MCMXCIV is M (1000) + CM (900) + XC (90) + IV (4) = 1994.

What is the largest number in Roman numerals?

Traditional Roman numerals can represent up to 3,999 (MMMCMXCIX). Numbers above 3,999 require a bar over letters to indicate multiplication by 1,000, which this converter does not support.

Is 'IIII' valid or should it be 'IV'?

In classical usage, IV is standard for 4 and IX for 9. However, IIII was historically common on clock faces and still appears there today. This converter accepts standard subtractive notation only.

Can I type Roman numerals in lowercase?

Lowercase works: xiv is read as XIV and converts to 14. Only the letters I, V, X, L, C, D and M are accepted; anything else shows an error.

Roman numeral to number converter

Convert any Roman numeral to its Arabic (decimal) equivalent instantly. Type any Roman numeral from I to MMMCMXCIX (1 to 3,999) and the converter shows the number in real time with validation. All conversion runs locally in your browser.

Enter a Roman numeral

How it works

The converter matches the largest symbol or subtractive pair at each position from left to right and adds the values: MCMXCIV is M + CM + XC + IV = 1,994. It then writes 1,994 back as a Roman numeral. If that differs from what you typed, as with IIII or IC, it reports a non-standard numeral and suggests the standard form when one exists (IIII becomes IV). All processing runs in JavaScript in your browser.

Processing runs in your browser

All conversions happen locally in your browser tab. Our servers are not involved at any point.

Related operations

For working with fractions (enter mixed numbers in improper form, such as 7/4), try the fraction calculator. To convert numbers between binary, hex, and decimal, use the number base converter. For unit conversions like inches to centimetres, see the unit converter.

Frequently asked questions

How do you read a Roman numeral?: Read from left to right and add each value, but when a smaller symbol comes before a larger one, subtract it: MCMXCIV is M (1000) + CM (900) + XC (90) + IV (4) = 1994.
What is the largest number in Roman numerals?: Traditional Roman numerals can represent up to 3,999 (MMMCMXCIX). Numbers above 3,999 require a bar over letters to indicate multiplication by 1,000, which this converter does not support.
Is 'IIII' valid or should it be 'IV'?: In classical usage, IV is standard for 4 and IX for 9. However, IIII was historically common on clock faces and still appears there today. This converter accepts standard subtractive notation only.
Can I type Roman numerals in lowercase?: Lowercase works: xiv is read as XIV and converts to 14. Only the letters I, V, X, L, C, D and M are accepted; anything else shows an error.

Last reviewed September 30, 2026

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