Password Strength Checker

No. The check runs entirely in your browser. Your password is held in the page while you look at it and is never sent to a server, logged or stored.

Entropy measures how unpredictable a password is, in bits. It is estimated as length times log2 of the character-set size. More bits means more possible combinations and a longer time to crack.

Each extra character multiplies the number of guesses an attacker must try, so length adds entropy fast. Adding more character types helps too, but a longer passphrase usually beats a short password full of symbols.

Length and unpredictability. Aim for 16 or more characters, mix lowercase, uppercase, digits and symbols, avoid common words, names, dates and keyboard patterns, and never reuse a password across accounts.

We assume an offline attacker trying about 10 billion guesses per second and that the password is found after roughly half the keyspace, so guesses equal 2 to the entropy bits divided by two. It is a rough guide, not a guarantee.

Common passwords and simple patterns are easy to guess no matter how long they look. If your password appears in well-known lists, it is forced to the lowest score regardless of its raw entropy.