Roman numeral converter

Convert Roman numerals, both ways

Type a number to get its Roman numeral, or type a numeral to read the value. Instant, accurate, and it never leaves your browser.

2025 is written MMXXV in Roman numerals.

Valid from 1 (I) to 3999 (MMMCMXCIX), the standard range of Roman numerals.

Popular numbers

The single values people look up most, with the tricky ones up front.

Browse all numbers in Roman numerals

Years in Roman numerals

For tattoos, wedding dates and anniversaries. Every modern year, ready to copy.

Browse all years in Roman numerals

Charts and references

Clean, printable tables from the first ten numerals to every year this century.

Tools and guides

Why Numerus

Two-way and live

Type on either side. Numbers to numerals and numerals back to numbers, updated as you type.

A real reference

Every number gets its own page: how the numeral is formed, where it appears, and nearby values.

Private and fast

All conversion runs in your browser. No sign up, no upload, nothing sent to a server.

Common questions

What is the range of Roman numerals?

Standard Roman numerals run from 1 (I) to 3999 (MMMCMXCIX). The Romans had no symbol for zero and did not write negative numbers. Values above 3999 use an overline, called a vinculum, to multiply a numeral by one thousand.

Why is 4 written IV and not IIII?

IV uses the subtractive rule: a smaller symbol placed before a larger one is subtracted. So I before V means five minus one, or four. You will still see IIII on many clock faces, a long-standing tradition rather than a mistake.

Are my numbers private?

Yes. Numerus does the maths in your browser. Nothing you type is uploaded or logged.