Password Strength Checker

About the Password Strength Checker

A strong password protects your accounts from brute-force attacks, credential stuffing, and dictionary attacks. But how do you know if your password is actually strong? This checker scores your password on a 0–4 scale by analyzing multiple strength factors: total length, character class diversity (lowercase, uppercase, digits, symbols), common dictionary patterns, and raw entropy.

Unlike simple length-only checks, this checker penalizes predictable patterns like sequential characters, repeated characters, and common words. A score of 0 means the password is trivially guessable, while 4 indicates excellent resistance to all common attack types. Use this checker to audit existing passwords or validate that new passwords meet your security standards.

When This Page Helps

Most password meters use simplistic rules that can be gamed easily. This checker combines multiple scoring dimensions to provide a more realistic assessment. It helps individuals choose better passwords and helps organizations set evidence-based password policies that actually improve security rather than just adding user friction.

How to Use the Inputs

1. Enter a password or passphrase to evaluate.
2. Review the overall strength score (0–4).
3. Check individual factor scores: length, diversity, patterns, and entropy.
4. Read the specific feedback and improvement suggestions.
5. Modify the password and re-check until you reach your target score.
6. Aim for a score of 3 or higher for important accounts.

Example Calculation

Tips & Best Practices

• Length is the most impactful factor — aim for 14+ characters.
• Use all four character classes for maximum diversity score.
• Avoid common substitutions like @ for a or 3 for e — attackers know these patterns.
• Random passphrases of 4–6 words score highest on both entropy and memorability.
• Never reuse passwords across accounts regardless of strength score.
• A password manager eliminates the need to remember complex passwords.

How Password Strength Scoring Works

This checker evaluates four independent dimensions of password quality and combines them into a composite score. Each dimension captures a different aspect of resistance to real-world attacks.

Length Score

Length is weighted heavily because it has the greatest mathematical impact on brute-force difficulty. Every additional character multiplies the search space by the charset size. We score on a 5-point scale with breakpoints at 6, 8, 12, and 16 characters.

Diversity Score

Using multiple character classes forces attackers to test a larger alphabet per position. Each class present (lowercase, uppercase, digits, symbols) adds one point. However, diversity alone cannot compensate for insufficient length.

Pattern and Dictionary Analysis

Common patterns dramatically reduce effective entropy. Our checker detects sequential runs, repeated characters, and well-known password patterns. These detections result in score penalties that reflect the real-world disadvantage of predictable passwords.

Entropy Assessment

The raw entropy in bits provides an objective mathematical measure of password strength. We map entropy ranges to scores that align with known brute-force capabilities of modern hardware.

Frequently Asked Questions

• What does each score level mean?

  0 = trivially guessable, 1 = very weak (easily cracked), 2 = fair (resists casual attempts), 3 = strong (resists most attacks), 4 = very strong (excellent protection). Most security guidelines recommend a minimum score of 3.

• Is this checker safe to use with my real password?

  This calculator runs entirely in your browser. No passwords are sent to any server. All processing happens locally on your device. However, for maximum caution, you can test passwords with similar characteristics rather than your exact password.

• Why does my password with special characters still score low?

  Special characters help, but they can't compensate for short length or predictable patterns. A 6-character password with symbols is still weak because the total entropy is too low. Length contributes more to security than character complexity.

• How is entropy calculated here?

  Entropy is estimated as length × log₂(charset size), where charset size is determined by the character types present. This assumes random character selection; real passwords with patterns or words have lower effective entropy.

• What are common patterns that reduce strength?

  Sequential characters (abc, 123), keyboard walks (qwerty), repeated characters (aaa), leetspeak substitutions (p@ssw0rd), and dictionary words all reduce effective password strength because attackers specifically target these patterns. Sharing these results with team members or stakeholders promotes alignment and supports more informed decision-making across the organization.

• Should I use this to set organizational password policies?

  It gives individual password assessment. For organizational policies, combine minimum score requirements with maximum age policies, breach database checks (like HIBP), and mandatory MFA. NIST recommends focusing on length minimums over complexity rules.