Password Strength Checker

How this is calculated

Entropy is estimated as password length × log2(charset size), where the charset size only counts the character classes actually present in the password — lowercase (26), uppercase (26), digits (10) and symbols (~32). This assumes the password was drawn uniformly at random from that charset, which overstates the real strength of predictable patterns: Password1! touches all four classes and scores the same formula-derived entropy as a truly random string of the same shape, even though it is far easier to guess. The issues list below exists to catch exactly that — common/dictionary passwords, repeated characters, and simple ascending or descending digit runs. The category bands (very weak / weak / fair / strong / very strong) are rough, commonly-cited thresholds on the resulting entropy, not a guarantee against any particular attack.