Password Strength Checker
Check password strength with entropy calculation
Password Strength Checker is a free online tool from BrowserUtils that check password strength with entropy calculation. It runs entirely in your browser — your data never leaves your device. No account required.
How to use Password Strength Checker
- 1 Paste or type your input into the editor above.
- 2 The tool processes your data instantly — right in your browser, with nothing sent to a server.
- 3 Copy the result with one click or continue editing your input.
About Password Strength Checker
Free online password strength checker. Analyze password entropy, character composition, and estimated crack time. Check against common password patterns. This tool runs entirely in your browser — your data is never sent to a server. Just paste your input, get instant results, and copy with one click. No sign-up or installation required.
Password Strength Checker specs
- Runtime
- 100% client-side (browser)
- Cost
- Free — no account, no rate limits, no usage caps
- Browser support
- Chrome 90+, Firefox 88+, Safari 14+, Edge 90+
- Part of
- 299 developer tools on BrowserUtils (100% client-side)
Questions
What is password entropy?
Password entropy measures the unpredictability of a password in bits. It is calculated as the length of the password multiplied by log2 of the character set size. A password with 80+ bits of entropy is considered very strong. Higher entropy means more possible combinations an attacker would need to try.
Is my password sent to a server?
No. All analysis happens entirely in your browser using JavaScript. Your password never leaves your device and is not transmitted over the network.
How many bits of entropy make a password strong?
Passwords with 60-79 bits are considered strong for most online accounts. Passwords with 80+ bits are very strong and suitable for encryption keys or high-security systems. Below 40 bits is considered weak and easily crackable.
Does the password strength checker detect common passwords?
Yes. The tool checks your input against patterns like dictionary words, keyboard sequences, and repeated characters. A password that matches common patterns will score lower even if it is long.
What makes a password stronger: length or special characters?
Length has a bigger impact on entropy than adding special characters. A 20-character lowercase passphrase is generally stronger than an 8-character password with mixed symbols, because each added character multiplies the total number of possible combinations.
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