Permutation Calculator
Find out how many ways you can arrange r items chosen from a set of n, where the order of selection matters.
What This Calculator Does
A permutation counts the number of distinct ordered arrangements you can make when selecting r items from a total of n items, where the sequence matters (choosing A then B is different from B then A).
The Formula
The number of permutations is calculated as nPr = n! / (n – r)!, where n! (n factorial) means multiplying all whole numbers from 1 up to n. For large values of n, this calculator uses logarithms internally to avoid overflow while keeping the result accurate.
When To Use It
Permutations are useful whenever order matters — for example, ranking finishers in a race, arranging letters in a code, or assigning distinct roles to people. If order does not matter, use a combination calculator instead.
Note: This tool is provided for general educational and planning purposes.