Password Strength Checker
Analyze password strength with entropy calculation, estimated crack time, and character diversity checks. Identifies common patterns and weak passwords. Your password never leaves your browser.
Parameters
Your password is analyzed locally — never transmitted.
Results
Other results (2)
Higher entropy means more randomness and better security
Why Choose Password Strength Checker
The Password Strength Checker analyzes your password by calculating its entropy in bits, estimating how long it would take to crack at 1 billion guesses per second, and detecting common vulnerable patterns. It checks for the presence of uppercase letters, lowercase letters, numbers, and symbols to give you a comprehensive strength rating from Very Weak to Very Strong.
- ✓Entropy calculation based on character set size and password length
- ✓Crack time estimation at 1 billion guesses per second
- ✓Detection of sequential characters, repeated patterns, and common passwords
- ✓Character set analysis including uppercase, lowercase, numbers, and symbols
How to Use
- 1Enter your password into the input field.
- 2The tool calculates the character set size based on which character types are present.
- 3Entropy is computed as log2(charset size) multiplied by the password length.
- 4A strength rating is assigned based on the entropy value.
- 5Common vulnerable patterns such as sequential characters and well-known passwords are flagged.
Frequently Asked Questions (FAQ)
What is password entropy?
Entropy measures the unpredictability of a password in bits. It is calculated as log2(charset size) times the password length. Higher entropy means more possible combinations and greater resistance to brute-force attacks.
How is crack time estimated?
Crack time assumes an attacker can test 1 billion passwords per second and on average needs to try half of all possible combinations. Real-world times may vary depending on the attacker resources and whether the attack is online or offline.
Is my password sent anywhere?
No. All analysis is performed entirely in your browser using client-side JavaScript. Your password is never transmitted over the network.
What makes a strong password?
A strong password has high entropy (at least 60 bits), which typically means a length of 12 or more characters using a mix of uppercase, lowercase, numbers, and symbols. Avoiding common words and patterns is also critical.
Why does a long password matter more than complexity?
Each additional character multiplies the number of possible combinations by the charset size. A 16-character lowercase-only password has more entropy than an 8-character password using all character types, because length contributes exponentially to the search space.
Authoritative References & Sources
NIST Password Guidelines (SP 800-63B)
View SourceWikipedia — Password strength
View SourceHave I Been Pwned
View SourceRelated Tools
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