Password Strength Checker

Is your password actually secure, or just long? Get a real entropy analysis, an estimated crack time, and specific tips to make it stronger — not just a vague 'weak/strong' label.

What is Password Strength Checker?

A Password Strength Checker evaluates how resistant your password is to guessing and brute-force attacks. It analyzes length, character diversity, entropy, and patterns to provide a strength rating and improvement suggestions.

Formula

Entropy (bits) = Length × log₂(Pool Size)

Pool Size = 26 (lower) + 26 (upper) + 10 (digits) + 33 (special) = 95 max

Score based on: length (50%), case mixing (15%), digits (15%), special chars (20%)

How to Calculate

Type or paste a password into the checker.
View instant strength rating (Weak to Very Strong).
Check entropy bits and estimated crack time.
Review the feedback tips for improvement.

Example

The password "Tr0ub4dor&3" scores ~56 bits of entropy (Good). It would take days to months to crack. A better approach: "blue-elephant-dances-midnight" has ~98 bits (Very Strong).

Key Benefits

Instant strength analysis with entropy
Clear crack time estimates
Actionable improvement tips
Completely private and free

Common Mistakes to Avoid

Using dictionary words or common phrases
Replacing letters with similar characters (e.g., 0 for O)
Using personally identifiable information
Making passwords too short or simple

Pro Tips

Use passphrases — long sentences that are easy to remember
Never reuse passwords across different accounts
Enable 2FA on all accounts that support it
Use a password manager to generate and store unique passwords

Key Terms Explained

Entropy: Measure of unpredictability in bits
Brute force attack: Trying every combination
Dictionary attack: Trying common words/phrases
Passphrase: A password made of multiple words

Common Use Cases

Testing new passwords before use
Evaluating existing password strength
Learning password security best practices
Auditing organizational password policies

Frequently Asked Questions

How is password strength calculated?

Strength is calculated using entropy (bits of randomness), length, character diversity, and pattern analysis. Higher entropy and diverse characters result in stronger passwords.

What is a good entropy score?

Entropy above 60 bits is good, above 80 bits is strong, and above 100 bits is very strong. A 12-character mixed-type password typically scores 70+ bits.

Why does length matter more than complexity?

Length exponentially increases password strength. A 20-character lowercase-only password (95 bits) is stronger than a 10-character mixed-type password (66 bits). Length always wins.

Is this tool storing my password?

No. All analysis happens in your browser. For security, consider typing a similar password rather than your actual one.

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