Password Entropy Calculator

See how entropy is calculated for a given character pool or word list, what patterns reduce that entropy in practice, and why the theoretical number is an upper bound rather than a guarantee.

Character-based entropy

86 characters in pool

Length: 16

Character pool

Lowercase a–z (26)Uppercase A–Z (26)Digits 0–9 (10)Symbols (24)

Calculation

H = L × log₂(N)
H = 16 × log₂(86) = 102.8 bits

Length (L) (L): 16
Pool or list size (N): 86
Entropy (H): 102.82 bits
Rating: Strong
Offline cracking at 10 billion guesses/sec: 14,185,389,241 millenniums

Comfortable against offline cracking with current hardware. Reuse is still the main risk.

A word list of 7,776 entries contributes 12.9248 bits per word.

Real-world patterns

The figure above assumes perfect randomness. Paste a candidate value to see how obvious structure reduces the real-world estimate.

Example value (optional)

Limitations. This is a model, not a measurement. It cannot tell whether a value came from a CSPRNG or from a human choosing something memorable, and it says nothing about storage, reuse, or whether the value has already leaked.

Real cracking tools try dictionary words and common patterns before any brute force, so a password that scores well on this page can still fall quickly in practice.