Password Entropy Calculator
Enter any password to measure its entropy and estimated crack time — all in your browser, nothing sent anywhere.
Length: 12 characters
Try an example:
Strength
Strong78.7 bits
Entropy Breakdown
78.7
Entropy bits
94
Charset size
Character types detected:
lowercase (26)uppercase (26)digits (10)symbols (~32)
Formula: 12 chars × log₂(94) = 78.7 bits
Estimated Crack Time
Online attack (100/sec)Centuries
Offline slow (1M/sec)Centuries
Offline fast (1B/sec)7.5e+6 years
Supercomputer (1T/sec)7.5e+3 years
Assumes attacker tries half of all possible combinations on average.
What is password entropy?
Entropy measures how unpredictable a password is. Higher entropy means more possible combinations an attacker must try, making brute-force attacks harder. It's calculated as:
Entropy = length × log₂(charset_size)- Below 36 bits — Weak, crackable quickly
- 36–60 bits — Moderate, acceptable for low-risk accounts
- 60–80 bits — Strong, suitable for most accounts
- 80+ bits — Very strong, recommended for critical accounts
How to maximize entropy
- Use longer passwords — length has the biggest impact
- Mix uppercase, lowercase, digits, and symbols
- Avoid dictionary words, names, and predictable patterns
- Use a password generator for truly random results