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Test your password strength with entropy analysis and a checklist.
🔒 Tested locally in your browser. Your password is never sent anywhere.
This tool analyzes your password's strength in real time and shows the estimated entropy, a strength rating, and a checklist of what would make it stronger. Everything runs in your browser — your password is never transmitted or stored.
Strength is based on entropy — the number of possible combinations an attacker would need to try. Longer passwords with more character types have higher entropy. A 12-character password using all four types (upper, lower, numbers, symbols) has about 78 bits of entropy, which is effectively uncrackable.
Adding length increases entropy exponentially, while adding character types increases it linearly. A 16-character lowercase password (75 bits) is stronger than an 8-character password using all four types (52 bits). When in doubt, go longer.
The Password Strength Checker handles password strength checkerdirectly in your browser. Paste or type your input, and the tool processes it instantly — no upload, no signup, no waiting. It's built for the moments when you need a quick transformation and don't want to leave your workflow.
Because the tool runs client-side, it's fast and private. Your text never touches a server, which makes it safe for sensitive content. The interface is keyboard-friendly and works on any device with a modern browser.
Common uses: people reach for this tool when they need to use a how strong is my password, password strength entropy checker, password security checklist, or password crack time estimator.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The Password Strength Checker is based on the following formula:
H = L × log₂(N) − penalties crack time ≈ 2^H ÷ guesses per second
Variables: H: entropy estimate (bits) L: password length (characters) N: charset pool size (26 lowercase, 52 both cases, 62 with digits, 95 with symbols) penalties: bits subtracted for dictionary words, repeats, and sequences guesses per second: attacker hash rate, e.g. 10^10 for fast offline cracking of weak hashes
Strength is estimated as brute-force entropy from length and charset, then reduced for predictable structure such as dictionary words, repeated characters, or sequences like abcdef. Dividing 2^H guesses by the attacker's hash rate converts entropy into an honest time-to-crack estimate.
Worked example: Step 1: Take the password summer2024, L = 10, using lowercase plus digits so N = 62. Step 2: H = 10 × log₂(62) = 10 × 5.954 ≈ 59.5 bits. Step 3: Subtract about 20 bits for two dictionary words plus a year pattern: H ≈ 39.5 bits. Step 4: Crack time ≈ 2^39.5 ÷ 10^10 ≈ 7.8 × 10^11 ÷ 10^10 ≈ 78 seconds. Result: weak despite decent length, because the pattern penalty leaves under 40 bits.
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