Password / Entropy Calculator
Estimate a password’s entropy in bits and how long it would take to crack, computed entirely in your browser.
Runs locally in your browser
Runs locally — nothing is sent anywhere.
Generate locally in your browser
Estimates assume random characters and a fast offline attack. Real passwords with words or patterns may be weaker.
What is the Password / Entropy Calculator?
This tool estimates the entropy of a password in bits based on its length and the character sets it uses, and translates that into an approximate offline crack time. Your password is never sent anywhere.
How to use it
- 1Type a password (it stays local).
- 2Read the entropy, strength rating and estimated crack time.
How it works
Entropy ≈ length × log2(pool size), where the pool grows with each character class used (lowercase, uppercase, digits, symbols). Crack time assumes a fast offline guessing rate.
Limitations & notes
- Entropy assumes random characters; real passwords with words or patterns are weaker.
- Dictionary and reuse attacks are not modeled.
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