Password Entropy Calculator
Type a password below to see how strong it really is. You will get its entropy in bits, an estimated crack time, a strength meter, and a checklist of improvements. Everything is computed inside your browser — your password never leaves your device.
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Private by design. This tool has no server calls. What you type stays in this page only, and nothing is saved or sent anywhere.
Nothing you type is stored, logged, or sent anywhere.
Strength overview
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0 bits of entropy
Length
0
Character set
0
Entropy
0 bits
Combinations
1
Estimated crack time
Rough estimates for a brute force attack trying every combination. Real attackers use word lists and patterns, so common words crack far faster than this.
| Attacker speed | Guesses per second | Estimated time |
|---|
Improvement checklist
How entropy is calculated
- Each character group adds to the pool: lowercase (26), uppercase (26), digits (10), symbols (32).
- Entropy in bits = length × log2(pool size). More bits means exponentially more combinations.
- As a rule of thumb: 28 bits is weak, 50 bits is decent, 80 bits is strong, and 128 bits is effectively uncrackable by brute force.
- Length matters most — a long passphrase of random words beats a short complex password.
- Do not reuse passwords across sites, and use a password manager to remember them.