Roman Numeral Converter

＋More features: convert a list at once, dates in Roman numerals

Convert several at once

Converts up to 20 items at a time, separated by commas or line breaks (tick “clock-face style” to write 4 as IIII).

Numbers or Roman numerals to convert (commas or line breaks, up to 20) Clock-face style (write 4 as IIII)

Write a date in Roman numerals

Turns a birthday or anniversary into a form such as MMXXVI・VII・XXIV (useful for ring engravings or design drafts).

Year Month Day

What this tool tells you

Type a number and see how it is written in Roman numerals (I, V, X, M and so on). It also works the other way, turning a Roman numeral you spotted on a clock face or in a film title back into an ordinary number. Handy for reading engraved years or the numbering of a title.

How to use

Choose the direction of conversion.
Enter a number (1–3999) or a Roman numeral (for example MMXXVI).
The result appears the moment you type — no button needed.

How it is calculated

There are seven basic symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000.
They are written from largest to smallest and added, but a smaller symbol placed directly before a larger one is subtracted (IV=4, IX=9, XL=40, XC=90, CD=400, CM=900).
Example: 1994 = 1000 (M) + 900 (CM) + 90 (XC) + 4 (IV) = MCMXCIV
When converting a Roman numeral to a number, the tool checks that it is written in standard form (IIII is rejected as an error).

Sources and assumptions

Conversion follows the standard notation for Roman numerals, including the subtractive rule.

Assumptions and notes

Roman numerals have no zero and no negative numbers; standard notation covers 1 to 3999.
Clock faces traditionally write 4 as IIII, but the main form of this tool uses the standard notation (IV).

Frequently asked questions

Why do clock faces use “IIII”?

There are several explanations, but it is generally attributed to the visual balance of the dial (matching VIII opposite it) and to tradition. The mathematically standard form is IV.

How is the year 2026 written in Roman numerals?

MMXXVI (two M=1000, two X=10, and VI=6). You often see this form in the production year at the end of a film's credits.

Can numbers of 4000 and above be written?

Standard notation goes up to 3999 (MMMCMXCIX). Beyond that there is a method of drawing an overline to multiply by 1000 (V̄=5000), but it is almost never used in everyday contexts, so this tool does not support it.