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Password Entropy Calculator

Estimate a password's entropy in bits from its length and character set, and see how that compares to common strength bands.

Entropy
78.8 bits
Strength
Strong
Possible combinations
5.40e+23

How it works

For a password drawn uniformly at random from a character set of size N, each character contributes log₂(N) bits of entropy, so an L-character password has entropy = L × log₂(N) bits. The character set sizes used here are digits (10), lowercase (26), lowercase+uppercase (52), plus digits (62), and plus the standard 33 printable symbols for 95 total.

The strength label (Very weak / Weak / Reasonable / Strong / Very strong) uses commonly cited entropy bands — under 28 bits is trivially guessable, 128+ bits is considered effectively unbreakable — as a rule of thumb, not a precise crack-time estimate, since actual crack time depends on attacker hardware and method, which this calculator doesn't assume.

FAQ

Why doesn't this show an estimated time to crack the password?

A real crack-time estimate requires assuming an attacker's guesses-per-second, which depends on hardware, the hashing algorithm used to store the password, and the attack method — none of which this calculator can know, and any number we hardcoded would go stale as hardware improves. Entropy in bits is the underlying, hardware-independent measure.

Does this check if my password is a common or leaked one?

No — entropy only measures the theoretical randomness of a password drawn uniformly from its character set. A password like 'Password1!' scores reasonably on entropy despite being one of the most commonly guessed passwords in real breaches, since entropy math assumes random selection, not human habits.

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