Roman Numerals Converter — number to Roman numeral

How it works

Roman numerals combine seven letters, each with a fixed value: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. A number is written by placing these from the largest value to the smallest and adding them up — so MDCCXXXII is 1000 + 500 + 100 + 100 + 10 + 10 + 10 + 1 + 1 = 1732.

The system is not purely additive. To avoid four identical letters in a row, the values 4 and 9 at every scale are written subtractively — a smaller letter placed before a larger one is subtracted from it:

• IV = 4 and IX = 9 (units)
• XL = 40 and XC = 90 (tens)
• CD = 400 and CM = 900 (hundreds)

The calculator applies these rules greedily: it peels off the largest place value it can at each step, so the numeral it produces is the single standard form.

Because the standard letters only reach M = 1000, the largest number expressible with them is 3999 = MMMCMXCIX. There is no zero and no negative in the classical system, so the calculator accepts whole numbers from 1 to 3999.

Worked example

Take 2026. Split it into 1000 + 1000 + 10 + 10 + 5 + 1. The two thousands are MM, the two tens are XX, the five is V and the one is I — giving MMXXVI. Notice there is no subtractive form here because none of the digits is a 4 or a 9.

Frequently asked questions

How do you write a number in Roman numerals?

Break the number into thousands, hundreds, tens and units, then replace each part with its Roman letters (M, D, C, L, X, V, I), writing them largest-first. Digits of 4 and 9 use the subtractive forms such as IV, IX, XL and CM. For example, 2026 becomes MMXXVI.

What are the seven Roman numeral letters?

They are I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Every Roman numeral is built from combinations of these seven symbols.

Why is 4 written IV instead of IIII?

To keep numerals short, the Romans avoided writing a symbol four times. Instead, a smaller letter before a larger one means subtraction: IV is "one less than five" (4), and IX is "one less than ten" (9). The same pattern gives XL (40), XC (90), CD (400) and CM (900).

What is the largest number in Roman numerals?

Using the standard letters, the largest value is 3999, written MMMCMXCIX. Larger numbers historically used a bar over a letter to multiply it by 1000, but that notation is not part of the everyday system, so this calculator stops at 3999.

Is there a Roman numeral for zero?

No. The Roman system has no symbol for zero and no way to write negative numbers; it was designed for counting and tallying. The smallest value it represents is 1 (I).

What year is MMXXVI?

MMXXVI is 2026: MM is 2000, XX is 20, V is 5 and I is 1, which add to 2026.