Entropy Calculator
Analyze the entropy, character composition, and crack resistance of any password or string.
How to Use
Enter a Password
Type or paste any password or string into the input box.
Review the Metrics
Entropy bits, character composition, and crack time estimates update instantly as you type.
Toggle & Copy
Use the eye icon to toggle visibility and the copy button to save your password.
Frequently Asked Questions
What is entropy?
Entropy measures the unpredictability of a password. Higher entropy (bits) means it's harder to guess. It depends on both the length and the variety of characters used.
What pool size means?
Pool size is the number of possible characters per position. A password using lowercase, uppercase, digits, and symbols has a larger pool than one using only lowercase.
How accurate are crack time estimates?
They are rough approximations based on the entropy formula (2^entropy / guesses_per_second). Actual times vary by attacker hardware, but they provide a useful relative comparison.
Is my data sent anywhere?
No. All computation happens locally in your browser. Nothing is transmitted to any server.