All Possible Combinations Generator

What this generator actually produces

Despite the "Allow repetition" checkbox being labeled as permutations, both modes of this tool generate combinations — groupings where order doesn't matter. The algorithm walks the item list left to right and only ever pairs an item with items that come after it in the list, so "apple, banana" is generated once and "banana, apple" never appears separately. If you need every ordered arrangement (where "banana, apple" counts separately from "apple, banana"), this tool will undercount them.

Worked example

Enter apple, banana, cherry, date (4 items) with length 2 and repetition off. The tool returns exactly 6 rows:

apple, banana
apple, cherry
apple, date
banana, cherry
banana, date
cherry, date

That matches the combinations formula C(4,2) = 4! / (2!·2!) = 24 / 4 = 6. Bump the length to 3 with the same 4 items and you get C(4,3) = 4 combinations instead. Check the "Allow repetition" box with length 2 and the same 4 items, and the count rises to 10, because now "apple, apple" and similar repeated pairs are valid.

When length exceeds available items

With repetition off, the tool blocks any length greater than your item count — you can't choose 5 unique items from a list of 4. Turn repetition on and there's no such ceiling, since items can repeat to fill any length.

Where this is actually useful

People use this for enumerating team pairings, testing which two-ingredient combinations to include in a menu, or generating small input sets for probability homework. It gets slow past a couple dozen items at longer lengths, since the number of combinations grows combinatorially — 20 items at length 10 already produces 184,756 rows.