Password Strength Checker

A Password Strength Checker is a free browser-based tool that measures how hard your password would be to guess and tells you exactly how to improve it. You type a password and instantly see a strength rating from Very Weak to Very Strong, its estimated entropy in bits, an approximate time to crack, and a checklist of what it is missing — all computed locally, so the password never leaves your device.

What does the password strength checker measure?

It scores a password on two things attackers care about: how large the pool of possible guesses is, and how predictable your specific choice is within that pool. The size of the guess pool comes from the character sets you used (lowercase, uppercase, numbers, symbols) and the length. Predictability comes from checking your password against a bundled list of the most common passwords, dictionary words, keyboard runs like qwerty, and repeated characters. A long password made of random characters scores high; a short dictionary word scores low even if it has a number tacked on the end.

How to check a password's strength

1. Type or paste a password into the field. Use the Show toggle if you want to verify what you entered.
2. Watch the strength meter update live as you type, moving through five colored levels.
3. Read the breakdown: length, character-set size, entropy in bits, and estimated time to crack.
4. Review the criteria checklist to see which requirements pass and which fail.
5. Follow the suggestions to strengthen the password, then re-test until it reaches Strong or Very Strong.

What is password entropy?

Entropy is a measurement, in bits, of how unpredictable a password is. Each extra bit doubles the number of guesses an attacker must make. This tool estimates entropy as length × log2(charset size) and then lowers the figure when it spots common passwords or predictable patterns, because those shrink the real search space dramatically. As a rough guide, under 40 bits is weak, 60 bits is decent, and 80 bits or more is very strong against offline attacks. The time-to-crack figure assumes a fast offline attacker testing about 10 billion guesses per second, which is a deliberately pessimistic, safe assumption.

Why check password strength in your browser?

Because a password checker that transmits your password is a security risk in itself. Everything here runs inside your own tab with no network request, so there is nothing to intercept, log, or leak. That makes it safe to test real passwords you actually use. When you find a weak one, the fastest fix is to replace it with a long random string from the Strong Password Generator, then confirm the replacement scores well here.

• Live meter: a five-level strength bar with color updates as you type.
• Real metrics: length, character-set size, entropy in bits, and time to crack.
• Criteria checklist: length, uppercase, lowercase, numbers, symbols, and no common patterns.
• Common-password detection: flags dictionary words and the passwords attackers try first.
• Actionable tips: specific, plain-language suggestions to raise the score.
• Fully private: analyzed 100% locally, nothing sent to any server.

Strength checking versus hashing and encryption

Checking strength tells you how resistant a password is to guessing, but it is only one part of good security. When a password is stored by a service, it should be saved as a slow salted hash — for example with the Bcrypt Hash Generator, which is designed to be deliberately slow so brute-forcing is expensive. Faster hashes like those from the SHA-256 Hash Generator and the older MD5 Hash Generator are excellent for file checksums and integrity checks but should never store raw passwords on their own. And when you need to protect the contents of a message rather than a login, reach for reversible encryption such as the AES Text Encryption tool. A strong password is the foundation that makes all of those layers worthwhile.

Frequently Asked Questions

Is my password sent anywhere when I test it?

No. The entire analysis runs in your browser with JavaScript. Your password is never transmitted, uploaded, logged, or stored — no network request is made with it, so it is safe to test passwords you really use.

How accurate is the time-to-crack estimate?

It is a conservative approximation, not a guarantee. It assumes an offline attacker guessing about 10 billion passwords per second and derives time from the password's entropy. Real-world attack speed varies with hardware and how the password is stored, so treat the figure as a relative guide.

What makes a password strong?

Length is the single biggest factor, followed by using a mix of character types and avoiding anything predictable. A random 16-character password, or a passphrase of several unrelated words, is far stronger than a short complex-looking password like P@ss1. Aim for at least 12 to 16 characters that are not based on dictionary words.

Why is my password marked weak even though it has symbols and numbers?

Complexity does not help if the base is predictable. Passwords like Password1! or Qwerty123 contain multiple character types but are still on common-password lists and follow obvious patterns, so attackers crack them quickly. The checker penalizes these regardless of surface complexity.

Does this tool store or remember my passwords?

No. Nothing is saved. When you close or refresh the page, whatever you typed is gone. There is no history, no account, and no server-side storage of any kind.

Should I use this instead of a password manager?

Use both. This tool helps you judge and improve individual passwords, but a reputable password manager generates, stores, and autofills unique strong passwords for every site so you never reuse one. The checker is a learning and verification aid, not a replacement for a manager.