How to Read and Write Roman Numerals

The seven symbols

Every Roman numeral is built from I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). There is no symbol for zero and no symbol for fractions in the standard system.

Symbols are normally written from largest to smallest. When that happens you simply add them: VIII = 5 + 1 + 1 + 1 = 8, and MDCLXVI = 1000 + 500 + 100 + 50 + 10 + 5 + 1 = 1666.

The subtraction rule

Instead of writing four of the same symbol, a smaller symbol is placed in front of a larger one to subtract it. Only six pairs are used:

• IV = 4 and IX = 9
• XL = 40 and XC = 90
• CD = 400 and CM = 900

Convert a number step by step

Split the number into thousands, hundreds, tens, and ones, then write each part. For 1994: 1000 = M, 900 = CM, 90 = XC, 4 = IV, giving MCMXCIV.

For 2026: 2000 = MM, 20 = XX, 6 = VI, giving MMXXVI. Working one place value at a time avoids most mistakes.

Read a Roman numeral

Go left to right. If a symbol is smaller than the one after it, subtract it; otherwise add it. In XLII, X is before L so it is −10, then L = +50, I = +1, I = +1, for a total of 42.

You will see Roman numerals on clock faces, book chapters, movie copyright dates, Super Bowl numbers, and the names of kings and popes.

Why the converter stops at 3999

The standard system repeats a symbol no more than three times, so the largest number you can write is MMMCMXCIX = 3999. Larger values needed extra marks like a bar over a letter, which are not part of everyday use.

The Roman Numerals Converter accepts whole numbers from 1 to 3999, or a Roman numeral, and converts in either direction instantly.