PrivTab

Roman Numeral Converter

Turn a number or a year into Roman numerals, or read a Roman numeral as a number, with the breakdown.

Runs in your browser · No uploads

–

The seven letters

LetterValueWritten before a larger letter, it subtracts
I1IV = 4, IX = 9
V5never
X10XL = 40, XC = 90
L50never
C100CD = 400, CM = 900
D500never
M1,000–
  • Nothing leaves your device
  • No server-imposed size limits
  • No sign-up, no watermark
  • Free

How to convert Roman numerals

  1. Type a number from 1 to 3999, or a Roman numeral.
  2. The other box fills in as you type.
  3. Copy the result.

How Roman numerals work

  • Letters are added from left to right: VI is 5 + 1 = 6.
  • A smaller letter before a larger one is subtracted, but only I before V and X, X before L and C, and C before D and M: IV is 4 and XC is 90.
  • A letter is never repeated more than three times in a row: 4 is IV, not IIII.
  • There is no zero, and the standard forms stop at 3999 (MMMCMXCIX).

Frequently asked questions

Why is IIII refused, when clocks use it?

Many clock faces show 4 as IIII, but the standard form is IV. The converter says which standard form your numeral should have.

Is anything sent anywhere?

No. The calculation happens in your browser as you type; nothing is sent anywhere.