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Roman Numerals

Convert between numbers and Roman numerals.

Free to use, no sign-up required. Roman Numerals is one of 198 tools built into Xenition, alongside a chat that can use them for you.

Converts numbers to Roman numerals and Roman numerals back to numbers, for dates, clock faces, book chapters and tattoos.

How to use Roman Numerals

  1. Type a number or a Roman numeral into the box, for example 2026 or MMXXVI.
  2. Digits are converted to a numeral; letters are converted to a number.
  3. Read the result below. A dash means the input is not a valid numeral or is out of range.

How it works

Numerals are built greedily from M 1000, CM 900, D 500, CD 400, C 100, XC 90, L 50, XL 40, X 10, IX 9, V 5, IV 4 and I 1. Numbers from 4,000 to 3,999,999 use the vinculum, a bar over a group that multiplies it by 1,000. When reading a numeral, only standard forms are accepted, so IIII and IC are rejected, and numerals are read up to 3,999.

Example

2026 is MMXXVI, 1994 is MCMXCIV and 3999 is MMMCMXCIX. 4000 is written as IV with a bar over both letters.

Questions about Roman Numerals

Why do clocks show IIII instead of IV?

It is a long-standing clockmakers’ tradition, often said to balance the dial visually against VIII. In standard notation 4 is IV, which is why this tool rejects IIII.

Is there a Roman numeral for zero?

No. Romans had no numeral for zero, so the tool does not convert 0 or negative numbers.

Use it from chat

You do not have to open Roman Numerals to use it. Ask Xenition in plain language and it runs the right tool, then carries the answer into whatever you are working on — a document, a spreadsheet, a deck.

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