Roman Numeral Converter

Why do we still have Roman numerals?

Why do we actually still have Roman numerals? Pretty strange, isn't it? Apparently we need more than one way to write numbers down. Because otherwise it gets too boring? Because we think in lists so much that after bullets, 123 and ABC we need even more to tick off our points?

• Lists. Outlines and legal documents use I, II, III as one more level next to 1, 2, 3 and a, b, c. Web pages have it built in: CSS has upper-roman and lower-roman as list styles.
• Names. The numeral is part of a name, not a count: Elizabeth II, Pope Leo XIV, Rocky IV, Super Bowl LX.
• Books. The front matter is numbered i, ii, iii, so page 1 can be where the main text begins.
• Clocks and credits. Clock faces, and the copyright year at the end of a film: MCMXCIV.

Read more: The Case for Roman Numerals in the 21st Century and Why we use 1, 2, 3.

How to read and write Roman numerals

Roman numerals use seven letters — I (1), V (5), X (10), L (50), C (100), D (500) and M (1000) — combined to represent any number. You read them from left to right, adding the values together: MMXXVI is 1000 + 1000 + 10 + 10 + 5 + 1 = 2026. The system has no zero and no decimal point, which is exactly why it eventually gave way to the numbers we use today.

The one twist is subtraction. To avoid writing four identical letters in a row, a smaller letter placed before a larger one is subtracted: IV is 4 (5 − 1), IX is 9 (10 − 1), XL is 40, XC is 90, CD is 400 and CM is 900. Only powers of ten (I, X, C) are used as subtractors, and only ever one at a time — so 8 is VIII, never IIX.

Standard Roman numerals run from 1 to 3,999 (MMMCMXCIX). For larger numbers the Romans drew a bar — a vinculum — over a numeral to multiply it by 1,000. This converter renders that bar automatically, so a number like 5,000 appears as V and 1,000,000 as M.

Whether you are decoding a date on a building, a movie copyright line, a clock face, or a tattoo, the rules above are all you need. Type your value in the box and the answer updates as you go.

Common Roman numerals

Learn more about Roman numerals