Roman numeral years.

Worked example

The year on a cornerstone reads MDCCCLXXXIV. Break it into M = 1000, DCCC = 800, LXXX = 80 and IV = 4. Adding them gives 1000 + 800 + 80 + 4 = 1884. In the other direction, 1999 is M (1000) + CM (900) + XC (90) + IX (9), which is MCMXCIX, and 2026 is MMXXVI.

How it works

The letters are I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Read left to right and add, except that a smaller letter placed before a larger one is subtracted. The standard subtractive pairs are IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). The largest number written in standard form is 3,999 (MMMCMXCIX).

Older inscriptions often use additive forms instead: IIII, XXXX and CCCC for 4, 40 and 400, and VIIII, LXXXX and DCCCC for 9, 90 and 900. IIII is still common on clock faces. The converter accepts these, gives the value, and shows the standard form. It rejects strings that are not well-formed, such as IC or IIX.

Sources and basis (opened 2026-10-08): Roman numerals - Wikipedia (letter values, subtractive notation, 3,999 maximum, additive forms such as IIII, XXXX, CCCC, VIIII, LXXXX and DCCCC, IIII on clocks).

FAQ

How do I read a year in Roman numerals?

Read left to right and add the values, subtracting a letter that comes before a larger one. MCMXCIX is M (1000) + CM (900) + XC (90) + IX (9) = 1999.

What is 2026 in Roman numerals?

MMXXVI: MM for 2000, XX for 20 and VI for 6.

What is the largest number in standard Roman numerals?

3,999, written MMMCMXCIX. Larger numbers need extra notation such as a bar over the letters.

Why do some inscriptions use IIII instead of IV?

Additive forms such as IIII, XXXX, CCCC, VIIII, LXXXX and DCCCC were often used, for example on clock faces. This converter reads them and also shows the standard form.

What does MDCCCLXXXIV mean?

It is the year 1884: M (1000) + DCCC (800) + LXXX (80) + IV (4).