Evaluate password resistance to modern GPU brute-force attacks with our free Password Strength calculator. Compute Shannon entropy bits, measure character pool complexity, and estimate crack times with 100% offline privacy.
Input any candidate password into the secure, locally processed field.
Watch the color-coded visual strength bar adjust instantly as you type.
Examine exact entropy bits, character pool size, and estimated brute-force crack time.
Calculates mathematical randomness in bits using entropy = length * log2(pool), providing an objective cryptographic strength metric.
Estimates crack times based on a modern high-speed GPU hash cracking rate of 10 billion combinations per second.
Your inputs never touch any server or disk. All evaluations happen entirely inside your local browser memory.
Password strength is objectively measured using Information Theory entropy in bits: E = L × log₂ (R), where L is password length and R is the character set pool size (e.g. 26 lowercase + 26 uppercase + 10 digits + 33 special symbols = 95).
Brute-force crack time estimates calculate total search space combinations C = Rᴸ and divide by an estimated hash evaluation rate (e.g. 10¹⁰ attempts/sec). Passwords under 30 bits crack instantly; passwords above 70 bits require centuries to break.
Length is exponential while character set size is linear. A 16-character passphrase using lowercase letters only (26¹⁶ ≈ 43.6 bits) is significantly harder to crack than an 8-character complex password (95⁸ ≈ 52.5 bits), highlighting the importance of length over character diversity.