Analyze any password's real-world strength, estimated crack time, and get concrete tips to improve it.
Choosing a password is easy; choosing a genuinely strong one is harder than most people expect, because human intuition about what "looks random" is usually wrong. This Password Strength Checker gives you an objective, mathematics-based assessment of any password you type, based on entropy calculation, character diversity, known common-password lists, and pattern detection — rather than a vague red/yellow/green bar with no explanation behind it.
As with every tool on this site, analysis happens entirely inside your browser. The password you type is never transmitted anywhere, never logged, and never stored — not even in temporary form. This is especially important for a strength checker, since typing a real password you actually use into an untrustworthy website would defeat the entire purpose of checking it in the first place.
Entropy, measured in bits, represents how many possible combinations an attacker would need to try to guess your password through brute force, assuming no shortcuts. Every additional bit of entropy doubles the number of guesses required. A password with 40 bits of entropy might be crackable within hours by a modern GPU cluster, while a password with 80+ bits of entropy could take longer than the current age of the universe using the same hardware. This tool calculates entropy directly from your password's length and the character sets it draws from, then translates that number into a plain-language estimated crack time so the result is actually meaningful.
Many people assume that jamming in extra symbols automatically makes a password stronger, but a short password with symbols can still be weaker than a longer password using plain lowercase letters, purely because of how exponential growth works with length. This checker rewards length substantially in its scoring, while still crediting the extra entropy that comes from mixing character types.
Beyond raw entropy, this tool checks your password against a list of extremely common passwords that repeatedly show up at the top of leaked password databases year after year — things like "123456", "password", and "qwerty". It also looks for repeated characters (like "aaaa") and predictable sequences (like "abc" or "123"), both of which dramatically reduce real-world security even if the raw character count looks respectable on paper. A password can technically have decent length and character diversity while still being trivially guessable because it follows a human-predictable pattern, and catching that gap is exactly what this analysis is designed to do.
Every analysis ends with specific, prioritized suggestions rather than just a score — for example, telling you exactly which character type is missing or flagging a detected sequence. Use these suggestions together with our Password Generator tool: check an existing password here to understand its weaknesses, then generate a fresh, high-entropy replacement built to the exact character requirements your account demands.
Security habits tend to stick best when they're built into an existing routine rather than treated as a special occasion. Consider running any password you're about to reuse through this checker before committing to it, especially for a new account signup, so that weak choices get caught at the moment of creation rather than discovered later after a breach has already occurred.
No. All analysis is performed locally in JavaScript within your own browser tab. Nothing is transmitted, logged, or stored.
It's a mathematical estimate of how long a determined attacker with significant offline computing power would need to guess your password through brute force, based on its entropy.
Length alone isn't enough if the password follows a common pattern, repeats characters, or matches a password found in known data breaches — all of which are checked here.
Generally yes, but remember that a password's real-world security also depends on it being unique to that one account and not reused anywhere else.
It's safe to do so since nothing leaves your browser, but as a best practice, consider generating and switching to a fresh, unique password afterward using the Password Generator tool.
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