Entropy Calculator
Calculate the theoretical entropy of a string based on its length and character set.
What is Entropy Calculator?
Calculate the theoretical entropy of a string or password in bits. The calculator analyzes the characters used, estimates the size of the possible character set, and uses the string length to calculate how many possible combinations the same character set and length could produce.
How to use
- Enter a string or password.
- Review its length and detected character sets.
- Check the estimated character set size.
- Review the calculated entropy in bits.
- Compare the theoretical number of possible combinations.
Features
- Entropy calculation in bits
- String length analysis
- Lowercase character detection
- Uppercase character detection
- Digit detection
- Special character detection
- Estimated character set size
- Possible combination count
Common Use Cases
- Password strength analysis
- Security education
- Random string analysis
- Token strength estimation
- Comparing password configurations
Example
Tr0ub4dor!
Length: 9 Character set size: 8 Entropy per character: 3.00 bits Total entropy: 27.00 bits Possible combinations: 134 217 728
FAQ
What is entropy in password security?
Entropy is a measure of the number of possible values a secret could have. Higher theoretical entropy means a larger possible search space.
How is password entropy calculated?
The theoretical entropy can be calculated as the string length multiplied by the base-2 logarithm of the estimated character set size.
Does a longer password always have more entropy?
A longer password generally has a larger theoretical search space when the character set and generation method remain comparable.
Does using more character types increase entropy?
Increasing the available character set can increase theoretical entropy, especially when the characters are selected unpredictably.
Does the calculator know how randomly a password was generated?
No. The calculator estimates theoretical entropy from the string length and detected character set. It cannot determine whether a human-created password was actually generated randomly.
Missing a feature?
If this tool doesn't cover your use case or is missing functionality, please let me know through the Contact page.
New improvements and features are added based on user feedback.