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Read privacy policyCheck how strong your password is. Tested locally — never sent to server.
In an era of constant data breaches and increasingly sophisticated cyber attacks, password security is more critical than ever. Weak passwords remain the number one cause of unauthorized account access, with billions of credentials exposed in breaches each year. Our free Password Strength Checker analyzes your passwords in real-time, providing entropy calculations, time-to-crack estimates, and actionable recommendations to keep your accounts secure.
Password strength is fundamentally about unpredictability — how difficult it would be for an attacker to guess your password. This is quantified through several metrics: entropy (measured in bits), character diversity, length, pattern detection, and resistance to dictionary attacks. Our checker evaluates all these factors to provide a comprehensive strength assessment.
The scoring criteria include: length (longer is exponentially stronger), character set diversity (mixing uppercase, lowercase, numbers, and symbols), absence of common patterns and dictionary words, lack of personal information, and overall entropy. A password scoring above 80% on all criteria is considered strong for most purposes.
Entropy measures the randomness or unpredictability of a password in bits. The formula is: Entropy = Length × log₂(Pool Size), where Pool Size is the number of possible characters. For a purely random password using all 94 printable ASCII characters, each character adds ~6.55 bits of entropy. A 12-character random password from this pool has ~78.7 bits of entropy.
However, humans rarely generate truly random passwords. Patterns, dictionary words, and predictable substitutions dramatically reduce effective entropy. The word "password" has near-zero effective entropy despite being 8 characters, because it appears in every attack dictionary. This is why our checker goes beyond simple character counting to detect these weaknesses.
| Password Type | Example Length | Entropy (bits) | Time to Crack* |
|---|---|---|---|
| Lowercase only | 6 chars | ~28 | Instant |
| Lowercase only | 8 chars | ~38 | ~5 minutes |
| Mixed case + numbers | 8 chars | ~48 | ~7 hours |
| Full charset | 8 chars | ~52 | ~3 days |
| Full charset | 10 chars | ~66 | ~26 years |
| Full charset | 12 chars | ~79 | ~200,000 years |
| Full charset | 16 chars | ~105 | ~Billions of years |
| 4-word passphrase | ~25 chars | ~51-64 | ~Years to centuries |
*Assuming 10 billion guesses per second (modern GPU cluster attacking hashed passwords)
Dictionary Words: Attackers start with dictionaries of common words, names, and phrases. "sunshine," "princess," and "football" are cracked instantly regardless of length. Even combining two common words ("bluesky") offers minimal protection against dictionary attacks.
Predictable Substitutions: Replacing 'a' with '@', 'e' with '3', or 'o' with '0' (leet speak) adds almost no security. Attack tools include these substitutions in their rule sets. "P@ssw0rd" is just as weak as "Password."
Keyboard Patterns: Sequences like "qwerty," "123456," "asdfgh," and "zxcvbn" are among the first patterns tested. Even complex-looking patterns like "1qaz2wsx" (vertical keyboard columns) are well-known to attackers.
Personal Information: Names, birthdays, pet names, favorite sports teams, and city names are trivially discoverable through social media. Attackers routinely compile personal wordlists from public profiles.
Password Reuse: Using the same password across multiple sites means one breach compromises all accounts. Credential stuffing attacks test stolen credentials against thousands of sites automatically.
Method 1 — Random Generation: Use a password manager to generate truly random passwords of 16+ characters using all character types. These are the strongest possible passwords but impossible to memorize — let the password manager handle storage.
Method 2 — Passphrases: Combine 4-6 random dictionary words: "correct-horse-battery-staple" (as popularized by XKCD). Use a word list of 7,776+ words, select randomly (dice or generator), and add separators. Memorable yet secure.
Method 3 — Sentence Method: Take a memorable sentence and use initials plus modifications: "I graduated from MIT in 2015 with honors!" → "IgfMi2015wh!". Unique to you, hard to guess, relatively memorable.
Even the strongest password can be compromised through phishing, keyloggers, or server breaches. Multi-factor authentication adds a second verification layer — something you have (phone, hardware key) in addition to something you know (password). Enable MFA on all accounts that support it. Hardware security keys (FIDO2/WebAuthn) provide the strongest protection, followed by authenticator apps (TOTP), and then SMS codes (least secure but better than nothing).
Length (12+ characters), character diversity (upper, lower, numbers, symbols), randomness (no patterns or dictionary words), and uniqueness (different for every account). A 16-character random password is virtually uncrackable.
Yes — all analysis runs locally in your browser using JavaScript. No passwords are sent to any server. For extra caution, you can test a password of similar structure and complexity rather than your actual password.
We estimate based on the password's entropy and an assumed attack speed of 10 billion guesses per second (modern GPU cluster). Time = 2^entropy / guesses_per_second. Real attacks may be faster (weak hashing) or slower (strong hashing like bcrypt).
Generally yes — each additional character multiplies the search space. However, a long password of repeated characters ("aaaaaaaaaa") or common phrases ("letmeinplease") is still weak. Length combined with randomness is the key.
Modern security guidance (NIST 2024) recommends NOT forcing regular changes unless there's evidence of compromise. Frequent changes lead to weaker passwords (incrementing numbers, etc.). Use strong, unique passwords and change only when necessary.
A dictionary attack uses lists of common passwords, words, names, and phrases to guess passwords. These lists contain millions of entries from past breaches. Any word found in a dictionary provides essentially zero security.
A 4+ word random passphrase can be both more secure and more memorable than a short complex password. "turquoise-anvil-glacier-notebook" has more entropy than "P@ss1!" and is far easier to remember and type.
Credential stuffing uses username/password pairs from one breach to automatically attempt logins on thousands of other sites. If you reuse passwords, one breach compromises all your accounts. This is why unique passwords per site are essential.
Guide
Password Strength Checker helps you generate a ready-to-use output from the input you provide without installing extra software. It is designed for students, creators, developers, and everyday users who need a quick, browser-based result with clear input and output.
Password Strength Checker helps you generate a ready-to-use output from the input you provide without installing extra software. It is designed for students, creators, developers, and everyday users who need a quick, browser-based result with clear input and output.
Using Password Strength Checker is simple: (1) Open the tool page, (2) Enter your values, text, or upload your file as prompted, (3) Click the action button or see instant results, (4) Copy, download, or use the output. No technical knowledge required.
Yes — 100% free with no hidden charges. Password Strength Checker is part of WoHoTech's free tools suite. Use it unlimited times without creating an account or providing payment information.
Yes. Password Strength Checker generates fresh, unique output each time you use it. You can regenerate results as many times as needed until you get exactly what you want — all completely free.
The generated output is yours to use for personal or commercial purposes. However, always review the result to ensure it meets your quality standards before using it in professional or published work.
No limits at all. Password Strength Checker is a free tool that you can use unlimited times. There are no daily caps, no account required, and no hidden charges for any feature.