TopToolsAiCalculate permutations (nPr), combinations (nCr), factorials and the versions with repetition for any n up to 300. Answers are exact, even for very large numbers.
Last updated: 21 Sep 2026
How to use Permutation & Combination Calculator
- Enter n, the total number of items.
- Enter r, the number of items you choose.
- Click Calculate to see nCr, nPr, n! and the working.
Frequently asked questions
What is the difference between a permutation and a combination?
In a permutation the order matters, so ABC and CBA are different. In a combination the order does not matter, so ABC and CBA count as one.
Why is nCr never larger than nPr?
Because nPr counts every ordering of each group of r items, and nCr = nPr ÷ r!.
Is this calculator free to use?
Yes, it is completely free, with no signup or account required.
Does my data get uploaded anywhere?
No. Everything is calculated in your browser and nothing is sent to our servers.
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