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Password Strength Checker

Analyze any password: strength score, predictable-pattern warnings, and improvement tips.

Password strength checker tool

Password strength is checked locally in your browser. Avoid testing highly sensitive active passwords if you are unsure about any implementation.

Long, unique passwords are usually stronger than short complex ones. Never reuse passwords across important accounts.
Generate a Strong Password

Pattern-adjusted estimate

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Random-character maximum

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Character pool

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Unique characters

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The pattern-adjusted estimate is roughly log2 of the guesses a pattern-aware attacker would need, and drives the score. The random-character maximum assumes every character was picked at random, so it only applies to generated passwords.

Strength results dashboard

Strength guidance is a local estimate and should not be treated as a guarantee.

Strength label

Not checked

Score—

Length

0 characters

Lowercase

0

Uppercase

0

Numbers

0

Symbols, spaces and emoji

0

Letters without case

0

Password checklist

12+ charactersNot checked
16+ charactersNot checked
Character varietyNot checked
No repeated runsNot checked
No sequencesNot checked
No keyboard patternNot checked
Not locally commonNot checked

Warnings

Enter a password to see warnings.

Suggestions

• Type or paste a password to check its strength.

The check runs in your browser. This page does not send the password to BlinkCalc, include it in analytics, or keep a history of what you type.

Local checking

Password analysis happens in your browser as you type.

Pattern-aware

The checker looks for common passwords and words, look-alike substitutions, repeats, sequences, keyboard patterns, and years.

Actionable tips

Results include readable suggestions you can apply before storing a password.

Dynamic Password Insights

Type a password to see local strength guidance.
Long, unique passwords are usually stronger than short complex-looking passwords.
This checker runs in your browser and does not send your password to BlinkCalc.
Use a trusted password manager to store strong passwords.

How Password Strength Checking Works

Strength checkers estimate how hard a password may be to guess.
Length is usually the biggest factor.
Variety can help when combined with length.
Predictable patterns reduce practical strength.
Reused or breached passwords are risky even if they look complex.
Local checking means this page does not send the typed password anywhere.

Length, Entropy, Patterns, and Breached-Password Notes Explained

Longer passwords create more possible combinations.
Simple entropy formulas assume random characters, so they overstate human-chosen passwords.
Repeated characters and sequences reduce strength.
Keyboard patterns like qwerty are easier to guess.
Common passwords are unsafe.
A password exposed in a breach should be changed.
Do not check real passwords against remote breach APIs unless privacy-preserving k-anonymity is clearly implemented.

Password Safety, Storage, and Reuse Notes

Use a unique password for every important account; do not reuse passwords across sites.
Store passwords in a reputable password manager.
Enable multi-factor authentication where available.
Change passwords exposed in known breaches.
Do not share passwords in chat, email, screenshots, or public documents.
Avoid saving password history in the browser.

Common Password Strength Examples

Short lowercase password: weak.
Password with common substitution: still weak.
Long passphrase: stronger.
Random 16-character password: very strong.
Reused password: risky regardless of complexity.
Password with keyboard pattern: weaker than it looks.
Generated password stored in password manager: recommended.

Scoring Limitations

The built-in word list is small and English-only, so uncommon words, names, places and non-English phrases are treated as random letters and can be overrated.
It cannot tell whether a password has appeared in a data breach or is reused elsewhere.
It cannot detect personal details such as your name, birthday, or pet's name.
No crack-time prediction is shown because real cracking speed depends on the site, its hashing and rate limits, and the attacker.
Treat the score as guidance; a password generator and password manager remain the safest option.

Account, Team, Developer, and Security Use Cases

Checking a new password idea.
Teaching password safety.
Reviewing team password guidance.
Comparing passphrases and random passwords.
Identifying weak patterns.
Creating security training examples.
Improving account hygiene.
Preparing password manager entries.
Developer demo environments.
Replacing reused passwords.

Privacy and Local Processing Notes

Password checks are processed locally in the browser.
No account is required.
This page does not send typed passwords to a server or include them in analytics.
Password history is not stored.
Clearing the field removes the password from page state where practical.
Browser extensions or software on your device can still see what you type.

Method Explanation

1. Type or paste a password.
2. Find predictable pieces: common passwords and words (with capitalisation, substitutions and reversal), repeats, sequences, keyboard paths, years, and digit or letter runs.
3. Estimate how many guesses each piece costs; characters matching no pattern are costed as random characters.
4. Pick the cheapest way to cover the whole password, since an attacker would.
5. Convert the estimated guesses to a 0–100 score and strength label.
6. Generate practical improvement tips.
7. Clear the password when finished.

Frequently Asked Questions

A password strength checker estimates how resistant a password may be to guessing by reviewing length, character variety, patterns, and common weak-password signals.

Related tools

More tools to try

Password Generator
Random String Generator
Username Generator
Hash Generator
JWT Decoder
UUID Generator

Related reading

Learn the formula, assumptions, examples, or context behind this tool.

How to create a strong passwordLearn what makes a password strong before you test one here.