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Password Entropy Meter

Type a password to see exactly how strong it is: entropy in bits, a strength rating, and how long it would take to crack. Everything runs 100% in your browser — your password never leaves your device.

Strength —
0
Entropy bits
0
Characters
0
Character set size
1
Possible combinations
Estimated time to crack (10 billion guesses/second): instantly

How to improve it

  • Type a password above to get personal tips.

What is password entropy?

Password entropy measures how unpredictable a password is, in bits. It is calculated from the size of the character set you used (lowercase, uppercase, digits, symbols) and the password length:

entropy = length × log₂(character set size)

For example, a 12-character password using all four character sets (94 symbols) has about 79 bits of entropy. Every extra bit doubles the number of guesses an attacker needs, so a few more characters make an enormous difference.

Note: this meter measures pure randomness. It does not know dictionary words or leaked passwords, so a common phrase like "Password123!" can score well here while still being guessable. Avoid real words, names and common substitutions.

Frequently asked questions

Password entropy measures how unpredictable a password is, in bits. It is calculated from the size of the character set you used (lowercase, uppercase, digits, symbols) and the password length: entropy = length × log2(charset size).

Under 28 bits is Very Weak, under 36 bits is Weak, under 60 bits is Fair, under 80 bits is Strong, and 80 bits or more is Very Strong. A 12-character password mixing all four character sets scores around 79 bits.

No. The meter runs 100% in your browser. Your password never leaves your device and nothing is uploaded or saved.

Length matters most. Use 16 or more characters with lowercase, uppercase, digits and symbols, and avoid names, dictionary words and repeated patterns like 1234 or qwerty.

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