Roman numeral converter

Convert between numbers and Roman numerals

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How it works

Roman numerals use seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1,000. Add the values from left to right, but a smaller letter before a larger one is subtracted. So IX is 9, and MMXXVI is 2,026.

Write the largest symbol that fits, subtract it, then repeat.

We follow the standard modern form, which goes from 1 to 3,999. Four in a row, such as IIII, isn’t standard, so we explain the right form.

Worked example. 2,026 is 1,000 + 1,000 + 10 + 10 + 5 + 1, which is MMXXVI. A smaller symbol before a larger one means subtract, so IV is 4.

Examples

Number	Roman numeral
4	IV
9	IX
40	XL
90	XC
400	CD
1999	MCMXCIX
2026	MMXXVI
3999	MMMCMXCIX

What this tool doesn’t cover

Numbers above 3,999 need special marks, which this doesn’t support.
There is no Roman numeral for zero.

Questions

Why is 4 written IV?

A smaller letter before a larger one means subtract, so IV is 5 minus 1.

What is the largest number?

In the standard form, it’s 3,999, written MMMCMXCIX.

Is there a Roman numeral for zero?

No. The Roman system had no symbol for zero.

How do I read Roman numerals?

Add the values from left to right, but subtract a smaller value that comes before a larger one. So XIV is 10 + 5 − 1, or 14.

How do I write a year in Roman numerals?

Break it into thousands, hundreds, tens and ones. For example, 2026 is MM, XX and VI, which makes MMXXVI.

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Sources: Encyclopaedia Britannica: Roman numeral (opens in a new tab)