Password Entropy Calculator
Calculate password entropy in bits, estimated crack time, and strength rating based on length and character set. Design stronger passwords for your systems.
How to Use the Password Entropy Calculator
- Enter password length.
- Select character set type.
- Click Calculate to see entropy, crack time, and strength.
使用例
- •Designing password policies for enterprise systems.
- •Comparing password strength for security audits.
- •Teaching security concepts to developers.
- •Evaluating passphrases vs complex password strategies.
計算式
Entropy = Length × log₂(charset size). Crack time = charset^length / attempts per second (10 billion/s assumed).
よくある質問
What is password entropy?
Entropy measures the unpredictability of a password in bits. Higher entropy means harder to crack by brute force.
How many bits of entropy is secure?
60+ bits is reasonable, 80+ is strong, 128+ bits is very strong for long-term security.
Does a longer password beat a complex one?
Length has a bigger impact than complexity. A 16-char lowercase password often beats an 8-char mixed password.