Free Roman Numeral Converter (+ Guide)

What is a Roman numeral converter?

A Roman numeral converter turns everyday numbers into Roman numerals and back.

You see them on clocks, in movie credits, on book chapters and Super Bowl names. This one checks the numeral you type too, and tells you if it isn't the standard form.

How Roman numerals work

There are 7 letters, each a value:

To write a number, take the biggest value that fits, write it, and repeat with what's left.

The 6 subtractive pairs keep it short: IV for 4, IX for 9, XL for 40, XC for 90, CD for 400 and CM for 900.

A worked example

Here's the example the calculator loads: 1994.

1994 = 1,000 + 900 + 90 + 4, so it's M + CM + XC + IV = MCMXCIV.

The date October 1, 2026 is X.I.MMXXVI month first, or I.X.MMXXVI day first.

Mistakes to avoid

These are the slips that end up engraved.

• Writing IIII for 4: the standard form is IV (clock faces are the famous exception)
• Subtracting the wrong pairs: 99 is XCIX, not IC
• Writing VX for 5: V is already 5
• Mixing up the date order on a tattoo: write down month first or day first before you book

If you type a numeral that isn't standard, like IIII, the calculator tells you what it adds up to and the standard way to write it.

Who is the Roman numeral converter for?

It's for anyone reading or writing a number the old way, and these tools help around it.

• Age calculator – for your exact age, then your birth year in numerals
• Percentage calculator – for everyday math
• Time zone converter – for dates across time zones

Check the numeral twice before it goes in ink.