Password Strength Checker: Estimate Entropy and Crack Time
Measure a password's entropy in bits and see roughly how long an offline attacker would need to guess it. Analysis is local, so it is safe to test a real password.
Quick answer
Password Strength Checker is a free online tool that measure a password's entropy in bits and see roughly how long an offline attacker would need to guess it. Analysis is local, so it is safe to test a real password.
- Cost: free, no signup or limits.
- Privacy: runs 100% in your browser; text is never uploaded.
- Works on: desktop and mobile browsers, offline once loaded.
- Category: Everyday Utilities.
Assumes 10 billion guesses per second against a fast hash.
How to Use
- 1.Type or paste the password you want to evaluate.
- 2.Read the strength score, entropy in bits and estimated crack time.
- 3.Apply the suggestions, or generate a stronger password with one click.
FAQ
Is it safe to type my real password?
Yes. Nothing is transmitted, logged or stored — the scoring runs in JavaScript on your device, and you can disconnect from the internet first.
How is entropy calculated?
Entropy is length multiplied by the log base 2 of the character pool size, with penalties for common words, repeats and keyboard sequences.
What crack speed is assumed?
Ten billion guesses per second, which reflects a well-funded offline GPU attack against a fast hash.