Combination Calculator
Calculate how many unordered selections are possible when choosing r items from a set of n distinct items.
Number of Combinations0
FormulanCr = n! / (r!(n-r)!)
n!0
r!0
(n-r)!0
How to Use the Combination Calculator
Enter the total number of items and the number selected to calculate how many unordered groups are possible.
Practical Example
If you choose 3 items from 5 distinct items and order does not matter, the number of combinations is 10.
Factors That Affect the Result
The calculation depends on whether order matters, whether repetition is allowed and whether the items are distinct.
Frequently Asked Questions
What is a combination?
A combination counts selections where order does not matter.
How is nCr calculated?
Use n! divided by r! times (n − r)! when repetition is not allowed.
How is it different from a permutation?
A permutation treats different orders as different outcomes; a combination does not.