Roman Numeral Converter

How to use the Roman numeral converter

• Number → Roman: choose this option and type a whole number from 1 to 3,999. The Roman numeral appears instantly with its breakdown by thousands, hundreds, tens and ones.
• Roman → Number: choose this option and type a numeral such as MCMXCIV. Upper or lower case both work. The converter checks that the numeral is written in standard form and, if it is not, explains the rule that was broken and suggests the correct numeral.

The seven Roman numeral symbols

Symbol	I	V	X	L	C	D	M
Value	1	5	10	50	100	500	1,000

Rules for writing Roman numerals

1. Write from largest to smallest and add the values: VI = 5 + 1 = 6, and MDC = 1,000 + 500 + 100 = 1,600.
2. I, X, C and M can repeat up to three times in a row: III = 3, XXX = 30, MMM = 3,000. Four in a row (IIII) is not standard.
3. V, L and D never repeat, because two of them would equal the next symbol (VV would be X).
4. Subtract by placing a smaller symbol first, but only in six pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). I can only be subtracted from V and X, X only from L and C, and C only from D and M. V, L and D are never subtracted.

These rules give every number from 1 to 3,999 exactly one standard form, which is why the converter rejects forms such as IIII, VV, IC or XM.

How to work out Roman numerals, step by step

Split the number into thousands, hundreds, tens and ones, convert each part, and join them. For 1994:

Place	Value	Roman
Thousands	1,000	M
Hundreds	900	CM
Tens	90	XC
Ones	4	IV
Total	1,994	MCMXCIV

To read a numeral, go the other way: split it into symbols and subtractive pairs, then add. MCMXCIV is M + CM + XC + IV = 1,000 + 900 + 90 + 4 = 1,994.

Roman numerals 1 to 20

Number	Roman	Number	Roman
1	I	11	XI
2	II	12	XII
3	III	13	XIII
4	IV	14	XIV
5	V	15	XV
6	VI	16	XVI
7	VII	17	XVII
8	VIII	18	XVIII
9	IX	19	XIX
10	X	20	XX

Tens, hundreds and thousands

Tens	Roman	Hundreds	Roman	Thousands	Roman
10	X	100	C	1,000	M
20	XX	200	CC	2,000	MM
30	XXX	300	CCC	3,000	MMM
40	XL	400	CD
50	L	500	D
60	LX	600	DC
70	LXX	700	DCC
80	LXXX	800	DCCC
90	XC	900	CM

Years in Roman numerals

Years often appear in Roman numerals in film and TV credits, on building cornerstones and on monuments.

Year	Roman numeral
1990	MCMXC
1999	MCMXCIX
2000	MM
2024	MMXXIV
2025	MMXXV
2026	MMXXVI

For a date of birth or anniversary, convert the day, month and year separately, for example 14 July 1995 becomes XIV · VII · MCMXCV. Use the age calculator if you also want to know an exact age from that date.

Roman numerals in chemistry

In chemical names, a Roman numeral in brackets gives the oxidation state of a metal that can form more than one ion. Iron(II) chloride is FeCl₂, with iron at +2, and iron(III) chloride is FeCl₃, with iron at +3. Copper(I) and copper(II) work the same way. To find the numeral, work out the charge the metal needs to balance the other ions in the formula.

Large numbers and the vinculum

The standard symbols stop at 3,999 (MMMCMXCIX), because there is no symbol for 5,000. Medieval and later writers drew a bar, called a vinculum, over a numeral to multiply it by 1,000, so a barred V means 5,000 and a barred X means 10,000. With bars the system can reach 3,999,999. This converter covers the standard range and does not draw bars.