Roman Numeral Converter

Roman numerals still turn up on clock faces, monarchs' names, book chapters and the copyright dates at the end of films and TV programmes. This roman numeral converter changes any whole number from 1 to 3,999 into standard Roman numerals and turns Roman numerals back into numbers, explaining how each numeral is built so you can check it yourself.

Quick answer: A roman numeral converter uses seven letters: I (1), V (5), X (10), L (50), C (100), D (500) and M (1,000). Symbols are added from largest to smallest, so 2026 is MMXXVI, while six pairs subtract, such as IV for 4 and CM for 900. The largest standard numeral is MMMCMXCIX, or 3,999.

What Are Roman Numerals?

Roman numerals use seven letters: I (1), V (5), X (10), L (50), C (100), D (500) and M (1,000). Numbers are written by adding symbols from the largest to the smallest, so 2026 is MM (2,000) plus XX (20) plus VI (6), giving MMXXVI.

Six pairs use subtraction instead: when a smaller symbol sits before a larger one, it is taken away. IV is 4, IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900. In standard form a symbol is never repeated more than three times in a row, which is why 4 is IV rather than IIII, and why the largest standard numeral is MMMCMXCIX, or 3,999.

How Do You Use the Roman Numeral Converter?

Step 1: Choose the Direction

You select Number to Roman to write a number in Roman numerals, or Roman to number to read one, and the result moves into the input box when you switch. Select Number to Roman to write a number in Roman numerals, or Roman to number to read one. When you switch, the current result moves into the input box, so you can check the conversion both ways.

Step 2: Enter the Number or Numeral

Type a whole number from 1 to 3,999, or type a Roman numeral in capitals or lower case. The tool flags non standard forms such as IIII or VX, explains the problem and suggests the correct way to write the value.

Step 3: Check the Breakdown

The breakdown table splits the value into thousands, hundreds, tens and units and shows the numeral for each part. If you also need the number written out in full, the number to words converter spells it out in English, which helps when you are checking a formal document or an invitation.

Step 4: Read the Result

The converted value appears at the top of the results, with the number of characters and the symbols used. Students comparing number systems can use the binary to decimal converter to see the same value written in base 2. The result updates as you type, so you can try several values quickly.

What Are the Main Roman Numerals?

Number	Roman numeral	Number	Roman numeral
1	I	90	XC
4	IV	100	C
5	V	400	CD
9	IX	500	D
10	X	900	CM
40	XL	1,000	M
50	L	2026	MMXXVI

The key Roman numerals are I for 1, V for 5, X for 10, L for 50, C for 100, D for 500 and M for 1,000, so 2026 is MMXXVI. Years are the most common use today, so 1999 becomes MCMXCIX and 2000 is simply MM. Clock faces are a well known exception, as many show IIII instead of IV for four o'clock, so do not be surprised if a watch or a church clock differs from the standard form used here.

Frequently Asked Questions