Password Strength Checker (Free) - Test Your Password

Most weak passwords are weak in predictable ways: too short, a common word, or a pattern attackers try first. A password strength checker shows you, in plain terms, how hard your password would be to guess. This guide explains what really makes a password strong, how entropy and estimated crack time are calculated, and how to test yours with the Password Strength Checker. It runs entirely in your browser, so the password you type is never uploaded, logged or stored.

What makes a password strong

Strength comes down to how many guesses an attacker would need. Two things drive that number: length and variety. Longer passwords have far more possible combinations, and mixing character types (lowercase, uppercase, digits and symbols) widens the pool each position can draw from.

The measure for this is entropy, expressed in bits. Each extra bit roughly doubles the number of possible passwords. A short, lowercase-only password might have 30 bits or fewer, while a long passphrase can exceed 70 bits. More bits means exponentially more guesses, which is why adding length helps more than swapping a single letter for a symbol.

Just as important is being unpredictable. A common word, a name, or a pattern like 123456 is weak no matter how it scores by raw math, because attackers try those first using lists of known passwords.

How to use the Password Strength Checker

Testing a password takes seconds:

1. Open the Password Strength Checker.
2. Type or paste the password you want to test.
3. Read the strength rating, the entropy score in bits, and the estimated time to crack.
4. Adjust your password, making it longer or more varied, and watch the score update live.
5. Settle on something that rates strong and that you can still remember.

Because the analysis is instant and local, you can experiment freely without any password leaving your device.

How length affects crack time

Length is the single biggest lever. The table below shows roughly how a random password's resistance grows as you add characters, assuming a mix of letters, digits and symbols. Exact numbers depend on attacker speed, so treat these as illustrative:

The jump from 8 to 16 characters is enormous because each added character multiplies the total combinations. This is why security guidance favors length above clever substitutions.

Use cases for a strength checker

A checker is useful in many moments:

• Before reusing or saving a password, confirm it is actually strong.
• Teaching yourself or a team why short passwords fail.
• Comparing a passphrase of several random words against a short complex string.
• Sanity-checking a generated password to see its entropy.

When you need a strong password rather than just a verdict on one, the Password Generator creates long, random passwords for you. A strength checker and a generator work well together: generate, then verify.

Tips and common mistakes

Keep these habits to stay safe:

• Favor length. Aim for at least 12 to 16 characters, and longer for important accounts.
• Use a passphrase of several unrelated words if random strings are hard to remember.
• Never reuse a password across sites. A strong password is still risky if a breach elsewhere exposes it.
• Avoid names, dates, keyboard patterns and dictionary words, even with simple substitutions like a 3 for an e, which attackers expect.
• Use a password manager so you can afford long, unique passwords everywhere.

The biggest mistake is trusting a short password just because it has a symbol. A symbol on an 8-character password does not save it.

Privacy: your password never leaves the browser

This is the most important point. The Password Strength Checker analyzes your password entirely on your own device. The text you type is never transmitted to a server, never logged and never stored. When you close the tab, it is gone.

That local-only design is why a checker like this is safe to use with real passwords, unlike a service that would send your input over the network. Even so, the safest test is on a password you are about to set rather than one already protecting an account. Explore more free developer tools or the full tools library, which all run in your browser the same way.