About the Permutation Calculator
Count arrangements of r items from n when order matters (nPr), with and without repetition.
Also known as: npr calculator, arrangements calculator, permutations formula, order matters.
How to use this calculator
- Enter total items n, arranged r.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Open “Step-by-step” to see how the answer was worked out.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
P(n, r) = n! / (n − r)!
Worked example
Using the values pre-filled in the calculator above:
- Total items n = 10
- Arranged r = 3
the calculator returns:
- P(n, r): 720
- With repetition nʳ: 1,000
Working
P(10, 3) = 10! ÷ 7! = 720