Password Entropy Calculator
Calculate the entropy of any password in bits. Understand the mathematical strength behind your password with our free entropy calculator.
Password entropy is a mathematical measure of how unpredictable a password is. Our entropy calculator computes the exact number of bits of entropy in your password based on its length and the size of the character pool used. Higher entropy means exponentially more combinations an attacker must try. Security experts recommend a minimum of 60 bits for important accounts and 80+ bits for critical systems. This tool helps you understand the math behind password security so you can make data-driven decisions about your credential strength.
How to Use This Tool
- 1. Enter your password in the calculator
- 2. View the entropy value displayed in bits
- 3. Compare against recommended thresholds (60+ bits for strong)
- 4. Experiment by adding different character types
- 5. Aim for 80+ bits for maximum security
Why Use This Tool
- Precise entropy calculation using information theory
- Educational tool for understanding password mathematics
- Helps set organizational password policies
- Visual strength meter correlates with entropy levels
- Completely private client-side computation
Frequently Asked Questions
How is entropy calculated?
Entropy = password length × log2(pool size). For example, a 12-character password using all 95 printable ASCII characters has about 79 bits of entropy.
What is a good entropy value?
40 bits is moderate, 60 bits is strong, and 80+ bits is very strong. Each additional bit doubles the number of possible combinations.
Does password pattern affect entropy?
Our calculator measures theoretical entropy based on character pool. Real-world entropy can be lower if the password contains dictionary words or common patterns.
How does entropy relate to crack time?
Crack time = 2^entropy / guesses_per_second. With 10 billion guesses/second, 60 bits of entropy takes about 36 years to crack.