Roman Numeral Converter

1. 01Type a number or a Roman numeralEnter a whole number in the first field, or a Roman numeral (using I, V, X, L, C, D, M) in the second field.
2. 02Read the converted resultThe other field updates automatically to show the matching value.

• Reading dates and inscriptionsDecode a Roman numeral date on a building, monument, or the end credits of a film.
• Book, chapter, and sequel numberingConvert a Roman-numeral chapter, volume, or sequel number (like Super Bowl LVIII) to a regular number.
• Homework and quizzesCheck a Roman numeral conversion for a class assignment or brain teaser.

• A well-known year1994 converts to MCMXCIV.
• A simple number9 converts to IX (one less than X, which is 10).
• The maximum supported value3999 converts to MMMCMXCIX — the largest number standard Roman numerals can represent.

Roman numerals combine seven symbols — I (1), V (5), X (10), L (50), C (100), D (500), and M (1000) — by adding their values from left to right. When a smaller symbol appears before a larger one, it is subtracted instead (for example, IV is 5 − 1 = 4, and CM is 1000 − 100 = 900). This tool follows the standard, modern convention for both directions of conversion.

Numbers must be whole numbers from 1 to 3999 — the range standard Roman numerals can represent without extra notation. There is no numeral for zero in classical Roman numeral notation, and repeating a symbol more than 3 times in a row (like IIII for 4, instead of IV) is treated as invalid, since it does not match the standard modern form.

The Romans had no symbol for zero in their standard numeral system. And since each additional thousand requires another M, very large numbers become impractical to write without extending the notation (historically done with a bar over a numeral to multiply it by 1000) — this tool sticks to the standard, unextended range most people actually use.

The conversion runs entirely in your browser. What you enter is never uploaded, stored, or shared, and closing the tab clears everything.

What is the highest number I can convert?

This tool supports the standard range of 1 to 3999, the largest number expressible with the basic Roman numeral symbols without special extended notation.

Why does IIII show as invalid instead of converting to 4?

IIII is a non-standard, older way of writing 4. The modern, widely used convention is IV (subtractive notation), so this tool only accepts and produces the standard form.

Is there a Roman numeral for zero?

No. The standard Roman numeral system has no symbol for zero.

Does capitalization matter when I type a Roman numeral?

No. You can type in uppercase or lowercase (like "mcmxciv" or "MCMXCIV") and the tool will handle it the same way.

Is my data saved?

No. Everything is calculated in your browser; nothing is sent to a server.