Password Strength Checker

How to use

1. Enter Password — Type or paste a password to analyze
2. Review Analysis — See strength score, entropy, and character breakdown
3. Follow Tips — Use the improvement suggestions to create a stronger password

What Is a Password Strength Checker?

A password strength checker analyzes a password and rates its resistance to various attack methods including brute-force, dictionary attacks, and pattern matching. This tool evaluates length, character diversity, common patterns, sequential characters, and repeating sequences to provide a comprehensive strength assessment.

How Password Strength Is Calculated

This tool evaluates multiple factors:

• Length: Longer passwords are exponentially harder to crack. Each additional character multiplies the number of possible combinations.
• Character variety: Using uppercase, lowercase, numbers, and symbols increases the search space attackers must cover.
• Pattern detection: Sequential characters (abc, 123) and repeating characters (aaa) reduce effective entropy.
• Common password detection: Known weak passwords like "password123" are flagged immediately.
• Entropy calculation: The tool estimates the bits of entropy based on character set size and password length.

Understanding Entropy

Entropy is measured in bits and represents the number of guesses needed to crack a password. A password with 40 bits of entropy requires about 1 trillion guesses. At 80 bits, the number exceeds the computational capacity of any current technology. This tool calculates theoretical entropy based on the character set used.

Common Password Mistakes

Many people unknowingly create weak passwords. The most common mistakes include using personal information (birthdays, names), using dictionary words with simple substitutions (p@ssw0rd), using the same password across multiple sites, and making passwords too short (under 10 characters).

Best Practices

Use a unique password for every account. Generate passwords randomly instead of making them up. Use a password manager. Enable two-factor authentication. Consider using passphrases — four or more random words joined together — which are both strong and memorable.

Privacy

This tool runs entirely in your browser. Your password is never sent to any server, logged, or stored.

Need to generate a strong password? Try our Password Generator. For hashing passwords, check our SHA-256 Hash Generator.

Frequently asked questions

Is my password sent to a server?

No. The password is analyzed entirely in your browser using JavaScript. It is never transmitted, stored, or logged anywhere.

What is password entropy?

Entropy measures the unpredictability of a password in bits. Higher entropy means more possible combinations an attacker would need to try. A password with 80+ bits of entropy is generally considered strong against brute-force attacks.

What makes a password strong?

Length is the most important factor, followed by character variety (mixing uppercase, lowercase, numbers, and symbols). Avoid common words, sequential patterns, and repeating characters.

Should I use this to check my real passwords?

This tool runs entirely in your browser and never sends data anywhere, so it's safe to use with real passwords. However, as a best practice, use a password manager to generate and store passwords.

Why does my long password still score low?

Length alone isn't enough. If your password uses only lowercase letters or contains common words and patterns, it will score lower because it's easier to guess despite being long.

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