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Permutation Calculator / Combination Calculator

Calculators > Permutation Calculator / Combination Calculator

4/20/15 We are experiencing some issues with the site calculator below. As a temporary fix, please use the above calculator!

The “Mathy” Way

When the order of items matters, that’s called a Permutation.

When the order of items doesn’t matter, that’s called a Combination.
Since we are not allowed to repeat items, we use the following formula:

Number of possible Permutations  
=    nr
Number of possible Permutations  
=    n!

(n – r)!
=    !

Number of possible Combinations  
=    (n + r – 1)!

r!(n – 1)!
=    ( + – 1)!

!( – 1)!
Number of possible Combinations  
=    n!

r!(n – r)!
=    !


The Visual Way

A form of the permutation problem that students commonly see is the “committee” problem. For example:

If there are 5 people, Jim, Jane, Bob, Susan, and Ralph, and only 3 of them can be on the new PTA committee, how many different combinations are possible?

In this example, there are 5 people to choose from (so n equals 5), and we need to choose 3 of them (so r equals 3).

Order doesn’t matter: if Jim is on the committee, he’s on the committee whether he’s picked first or last. Repetition isn’t allowed because Susan can’t be on the committee twice (even if she really wants to be!)

So, if we use the “mathy” way from above, we know the formula is:

Number of possible Combinations  
=    n!

r!(n – r)!

And we input the number 5 for n, and 3 for r, and so we know that there 10 possible combinations. But what does that actually mean?

Combinations Generator

I’ll show you using our generator:

All possible items:

  • No.
  • No.


Permutation Calculator / Combination Calculator was last modified: April 22nd, 2015 by Stephanie

37 thoughts on “Permutation Calculator / Combination Calculator

  1. Frank

    I am interested in how many choices a person would have to divide 36 months among 3 people?

  2. Andale

    Hi, Frank,
    I’m not sure I understand your question completely but it might be the fundamental counting principle could help. 36 events (months), 3 ways to order each month so that’s 3^36.

    If you can clarify a bit and post on our forum, one of our mods will be happy to help!

  3. Frank

    Here is the problem.
    A person has 36 months to divide among 3 people.
    How many different combinations could there be.
    For example one combo would be 12 months each.

  4. Art

    I like the calculator, however, my problem would need a slightly different formula that I haven’t found.
    PROBLEM: I have 25 choices, and want to know the total number of combinations possible. Since I want combinations, not permutations, order does not matter. To keep it simple, repetition is not allowed. The combinations can be of any number of choices (r=1,2,3,…25). I can use the calculator and solve sequentially for r=1, r=2, r=3, etc., then sum the answers. However, there should be an equation that would solve the problem in one calculation. Can you show me that equation?

    Thank you,


  5. Andale

    Well, Art. The calculator uses the combinations formula (n!/(n-k!)k!). As you want to know k for all possible choices (1 to 25). I don’t know of a single equation other than a summation equation (Σ (n!/(n-k!)k! from n=1 to n=25)) I would suggest Excel. Copy the formula to 25 cells and then use autosum.

  6. Art

    OK, thanks. I appreciate the quick reply, and will probably use the spreadsheet method you suggested.


  7. Rachel G.

    So if i have a 4-input combination lock that requires pink, green or purple as the input options. How many combinations are possible and can you list them? The order doesnt matter and they can be repeated. It would be really amazing if i could get this lock open! Ive been trying with no luck all weekend. Thanks in advance!

  8. Andale


    {pink,pink,pink,pink} {pink,pink,pink,green} {pink,pink,pink,purple} {pink,pink,green,pink} {pink,pink,green,green} {pink,pink,green,purple} {pink,pink,purple,pink} {pink,pink,purple,green} {pink,pink,purple,purple} {pink,green,pink,pink} {pink,green,pink,green} {pink,green,pink,purple} {pink,green,green,pink} {pink,green,green,green} {pink,green,green,purple} {pink,green,purple,pink} {pink,green,purple,green} {pink,green,purple,purple} {pink,purple,pink,pink} {pink,purple,pink,green} {pink,purple,pink,purple} {pink,purple,green,pink} {pink,purple,green,green} {pink,purple,green,purple} {pink,purple,purple,pink} {pink,purple,purple,green} {pink,purple,purple,purple} {green,pink,pink,pink} {green,pink,pink,green} {green,pink,pink,purple} {green,pink,green,pink} {green,pink,green,green} {green,pink,green,purple} {green,pink,purple,pink} {green,pink,purple,green} {green,pink,purple,purple} {green,green,pink,pink} {green,green,pink,green} {green,green,pink,purple} {green,green,green,pink} {green,green,green,green} {green,green,green,purple} {green,green,purple,pink} {green,green,purple,green} {green,green,purple,purple} {green,purple,pink,pink} {green,purple,pink,green} {green,purple,pink,purple} {green,purple,green,pink} {green,purple,green,green} {green,purple,green,purple} {green,purple,purple,pink} {green,purple,purple,green} {green,purple,purple,purple} {purple,pink,pink,pink} {purple,pink,pink,green} {purple,pink,pink,purple} {purple,pink,green,pink} {purple,pink,green,green} {purple,pink,green,purple} {purple,pink,purple,pink} {purple,pink,purple,green} {purple,pink,purple,purple} {purple,green,pink,pink} {purple,green,pink,green} {purple,green,pink,purple} {purple,green,green,pink} {purple,green,green,green} {purple,green,green,purple} {purple,green,purple,pink} {purple,green,purple,green} {purple,green,purple,purple} {purple,purple,pink,pink} {purple,purple,pink,green} {purple,purple,pink,purple} {purple,purple,green,pink} {purple,purple,green,green} {purple,purple,green,purple} {purple,purple,purple,pink} {purple,purple,purple,green} {purple,purple,purple,purple}

  9. matthew

    Ok so i have a lock that i need the combo to, i had it in third grade and the numbers are only 1-9 with the usual, only three in the combination. I need all the possible combos w/ repeating numbers hoping i can see the combo and remember and if not go through all the numbers manually.

  10. Andale

    Hello, Matthew,
    Unfortunately I’m not not able to answer all stats question here on the site. Could you please post your question on our forums?

  11. Al

    Hello! I really like that the combinations generator physically shows all of the combinations. However, I need a slightly different calculator. I need to calculate and show all the combinations that 15 people can be in two groups (one of 7 and one of 8).

  12. Jefferson

    This calculator works great because its assuming each N has the EXACT same number of R. What if some N have R=4 and some N have R=5?

  13. Andale

    In that case the combinations formula itself would chance, so you’d have to do two computations (the calculator is based on the combinations formula).

  14. Andy

    Thank you for your site. Could you tell me the formular for calculating possable combinations for 2 numbers and 2 letters Eg starting with 00AA

    Thank you in advance for your help


  15. Andale

    Hello, Andy,
    Could you please post this on our homework help forum? One of our moderators will be happy to help.


  16. Andale

    Hello, AJ,
    Can you post on our homework help forum, please. One of our mods will be happy to help.

  17. Robert williams

    I have a locking device with 10 buttons which can all be pressed up to 3 times. The buttons can be pressed in any order, therefore the locking device is a combination lock. The user can set the code using any number of buttons from just one button to all the buttons.
    I am trying to establish how many combinations they would be for this type of device.

    Any help would be welcome.



    i think that it;s fabulous that you came up with such an impressive way of calculating things,
    loved it

  19. Eric McCrea

    I have a lock that consists of 5 numbers. Please help. The numbers are 56890. I need every different order to try and unlock it. Please help and thank you in advance.

  20. Jacob

    Can you please help me to find the right way to calculate this problem I have. I have 12 people in a group and in need to find the total number of possible pairs of 2. If what I have done is correct would it be 66?

    Thanks in advance

  21. sherri

    i would like to find out how many different 12 digit combinations can you get using only numbers 1,2,3 and could you please list these different combinations for me.

  22. Dwain

    Is it possible for me to get a list of all five set combination from 1 and 22
    eg 3,8,22,12,9

  23. Oljeg

    Hi, I am trying to find the solution (formula) for doing the following:
    For any number of players (divisible by three), I need to calculate a number of rounds (in my case 8) for three players to play each other without any repetition.
    So the first round of etc. 21 players would be:
    1,2,3 4,5,6, 7,8,9 10,11,12 13,14,15 16,17,18 19,20, 21 and I am looking for the combinations for the next 7 rounds so that no one plays the same player again.


  24. Andale

    Hi, Dwain,
    Due to the volume of questions I get, I’m unable to answer every one. Could you post your question on the help forum? One of our mods will be happy to help. Thanks!

  25. Andale

    Hello, Oljeg,
    Due to the volume of questions I get, I’m unable to answer every one. Could you post your question on the help forum? One of our mods will be happy to help. Thanks!

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