Password Entropy Calculator
Measure password entropy in bits, detect character pools, and estimate brute-force crack time at a chosen guess rate.
Password Entropy and Crack Time
Password entropy measures how many guesses an attacker needs on average to find your password by brute force. Longer passwords and larger character pools increase entropy and improve resistance to automated guessing.
Entropy Formula
$$E = L \times \log_2(R)$$
Where $L$ is password length and $R$ is the size of the character pool built from every symbol type present in the password. The average crack time uses half the keyspace: $2^{E-1}$ guesses divided by your selected guess rate.
Related tools: Hash Identifier, ASCII Converter, and Even Parity Calculator.
Frequently Asked Questions
How many bits of entropy is enough?
Casual accounts often need 25-30 bits. Important accounts should aim for 60-80 bits or more.
Why detect character pools automatically?
Entropy depends on which symbol types are actually used. A lowercase-only password has a smaller pool than a mixed-character password.
Does entropy alone guarantee safety?
No. Common or leaked passwords can be cracked quickly even with decent entropy. Uniqueness matters too.
What guess rate should I use?
One billion guesses per second is a common high-end offline attack assumption. Lower values model slower online throttled attacks.
Related Tools
Fourier Number Calculator
Concrete Block Fill Calculator
Latent Heat Calculator
Rounding Numbers Calculator
JSON Diff
XML Minifier
Triangle Vertices Calculator
Rectangular Prism Calculator
Dog Size Calculator
Adderall Dosage Calculator
Order of Magnitude Calculator
Check Spoofed Unicode Text
C Sharp Viewer
LinkedIn Share Link Generator
Convert Image to Data URI
Gutter Design Calculator
Upload Time Calculator
Flip A Coin
Magnus Force Calculator
Convert Time Between Countries