Everyday utility

Permutation and Combination Calculator

Calculate permutations P(n,r) and combinations C(n,r) — the number of ways to arrange or select r items from n. Use this Data and utilities tool to enter your numbers, review the result, and understand the key assumptions before making the next decision.

What you get
A focused calculator, clear explanation, common questions, and useful next tools.
Quick intro
Calculator
Result
Explanation
Common questions
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Calculator tool

How this calculator works
The result depends on the numbers you enter and the assumptions shown below.

Permutation P(n,r) = n!/(n−r)! counts ordered arrangements. Combination C(n,r) = n!/(r!(n−r)!) counts unordered selections. Use P when order matters (passwords), C when it doesn't (lottery).

Review the inputs carefully and treat the output as an estimate. For decisions involving money, taxes, health, law, or security, compare the result with trusted professional guidance when needed.

Frequently asked questions

When do I use permutation vs. combination?

Use permutation when order matters (e.g., finishing positions in a race). Use combination when order doesn't matter (e.g., selecting a committee).