Password Entropy Calculator
Calculate the exact entropy of a password based on character set and length.
About This Tool
Calculate the exact entropy of a password based on character set and length. All operations are performed entirely in your browser for maximum security. No data is ever sent to any server.
Security Notice: This tool uses
crypto.getRandomValues(), a cryptographically secure random number generator built into your browser.
Frequently Asked Questions
What is password entropy?
Entropy = log2(charset_size ^ length). It measures how unpredictable a password is.
What charset sizes are common?
10 (digits only), 26 (lowercase), 52 (mixed case), 62 (alphanumeric), 95 (all printable ASCII).