Combinations, permutations, password complexity, and counting calculators. Browse our free combinatorics tools below — all calculators are instant, accurate, and require no sign-up.
Combinations with Repetition Calculator — Calculate multiset combinations C(n+r-1, r). Stars and bars visualization, full enumeration for small cases, distribution patterns, and reference tables.
Password Combination Calculator — Calculate password combinations, entropy bits, and brute-force crack time. Compare password length and character set impacts on security strength.
Combinations without Repetition Calculator — Calculate C(n, r) combinations without repetition. Full enumeration for small cases, Pascal's triangle row, probability of a specific combo, and reference table.
Permutations without Repetition Calculator — Calculate P(n, r) ordered arrangements without repetition. Step-by-step position filling, full enumeration, comparison with combinations, and reference table.
Permutations with Repetition Calculator — Calculate ordered arrangements with repetition (n^r). Supports variable pool sizes per position, position breakdown, entropy, and reference tables.
Possible Combinations Calculator — Calculate all four types of counting: permutations/combinations with/without repetition. Decision guide, side-by-side comparison, visual size chart, and common examples.