How the Password Strength Checker calculates your score

Password strength is not a single magical number — it’s an estimate of how hard a password is to guess under common attack scenarios. This checker combines three practical ideas: length, character variety, and pattern penalties. It then gives you a simple 0–100 score with clear tips for improvement.

First, the tool looks at length. Longer passwords drastically increase the number of possible combinations an attacker must try. A 16‑character password can be astronomically stronger than a 10‑character password, even if the 10‑character password has symbols. That’s why the score boosts quickly when you pass common safety thresholds like 12, 14, 16, and 20 characters.

Next, we estimate character set size (also called the alphabet size). If you use only lowercase letters, the “alphabet” is about 26 characters. Add uppercase, and it becomes ~52. Add digits and it becomes ~62. Add symbols and it grows further (often 80–90+ depending on what symbols are allowed). A bigger character set increases the possible combinations — but it only helps a lot when the password is also reasonably long.

Then we apply pattern penalties because real attackers don’t brute‑force randomly first — they use smarter guesses. The checker flags common patterns that reduce strength: repeated characters (aaaaaa), simple sequences (123456, abcdef), keyboard runs (qwerty), and “word + digits” formats (Summer2026!). These passwords might look complex, but they appear early in real‑world guessing lists.

We also show an entropy estimate in bits. The “textbook” approximation is: entropy ≈ length × log2(character_set_size). This comes from counting how many different strings exist if each character is chosen independently at random from a set. For example, a 16‑character password from a 62‑character set has: 16 × log2(62) ≈ 16 × 5.95 ≈ 95 bits of estimated entropy.

Important: entropy is an upper bound for human‑made passwords. If you choose predictable words, patterns, or personal info, the “effective entropy” is lower. That’s why the pattern flags matter: they subtract points and convert “looks complex” into “actually guessable” when patterns are detected.

We also show rough crack‑time hints for two scenarios: online guessing (slow, rate-limited, like a website login) and offline guessing (fast, like cracking a stolen password hash). Online attacks might be limited to tens or hundreds of guesses per second. Offline attacks can be billions of guesses per second for weak hashing or specialized hardware. Your real risk depends on the site’s security, hashing algorithm, and whether you use MFA — so treat crack times as educational, not guaranteed.

Password strength examples (and what to fix)

These examples show why “complex” isn’t the same as “strong”, and how small changes can create big gains. (Don’t copy these exact passwords — create your own unique versions.)

• Password: Summer2026!
• Why it’s weak: common word + year + symbol is a classic pattern in leaked lists.
• Fix: use a long passphrase: summer-lakes-quiet-moon-2026 (or generated random).

• Password: F7!qZ2#k
• Why it’s only “okay”: 8 characters may be brute‑forced offline faster than you think.
• Fix: keep the randomness but increase length: F7!qZ2#k9v@Lx3P!

• Password: river-candle-otter-sapphire-quiet
• Why it’s strong: long length gives high search space even with simple characters.
• Fix: ensure it’s unique per account, and avoid famous quotes.

• Password: aaaabbbb1234
• Why it’s weak: repeats + numeric sequence collapses effective entropy.
• Fix: remove repeats and patterns; use generator or a longer phrase.

A good rule: if you can “explain” your password pattern in one sentence, an attacker can probably guess it faster than a truly random password or a long, unique passphrase.

Score components (0–100)

To keep results consistent across devices, the score is built from several components that add up and then clamp to the 0–100 range. The exact number isn’t a security guarantee — it’s a ranking tool to help you improve.

Length is weighted heavily. The tool awards more points as length increases, with noticeable boosts at 12, 14, 16, and 20 characters. Below 10 characters is penalized because short passwords are often crackable offline.

Using different character types increases the search space. Points are awarded for including: lowercase, uppercase, digits, and symbols. (A long passphrase may score strong mainly from length even without symbols.)

If the password includes repeating runs (aaaa), sequences (abcd, 1234), keyboard patterns (qwerty), or common passwords/words, points are subtracted. This is because attackers try common patterns first, so the password is effectively easier than raw entropy suggests.

The checker can’t know whether you reuse this password elsewhere (that’s a behavior, not a string property), so it reminds you: the strongest password becomes weak if reused. Breaches + password reuse are a top driver of account takeovers.

Finally, we produce a label: Weak, Fair, Good, Strong, or Very Strong — and we generate tips that target what your password is missing (length, variety, or pattern issues).

Frequently Asked Questions

• Does this tool save or upload my password?

  No. The analysis runs in your browser only. There are no network requests. Still, for peace of mind, avoid testing real passwords on shared/public devices.

• Why does a long passphrase score higher than a short complex password?

  Because length grows the search space exponentially. A 20‑character passphrase can be far harder to brute‑force than a 9‑character “complex” password, even if the shorter one has symbols.

• Is the crack-time estimate accurate?

  It’s a rough educational hint. Real cracking depends on hashing algorithms, salts, GPU/ASIC hardware, and the attacker’s strategy. Treat it as a “ballpark”, not a promise.

• What’s the single best upgrade I can make today?

  Stop reusing passwords and turn on MFA. Then use a password manager to generate 16–24 character unique passwords.

• What’s a good master password for a password manager?

  A long, unique passphrase (4–6 random words) that you’ve never used anywhere else, ideally 20+ characters. Example format: river-candle-otter-sapphire-quiet.

• Should I include symbols?

  Symbols can help, but only if your password is already reasonably long. Many sites also restrict symbols, so the safest strategy is usually: long + unique, with symbols as a bonus.