Password Strength & Entropy Checker
Test the entropy and brute-force resistance of your passwords.
Type a password into the box below to instantly evaluate its mathematical strength. This tool analyzes the length, character variety (entropy), and structural complexity of your input to determine how resistant it is against modern automated brute-force attacks.
100% Client-Side Privacy: To guarantee absolute security, this specific tool is designed so that your typed password is never sent over the network to our servers. The entropy analysis happens instantaneously within your own web browser's memory. We do not store, log, or transmit your password.
How it works
When you type a password, the tool calculates its Information Entropy, measured in "bits." Entropy is a mathematical concept that describes how unpredictable a sequence of characters is. The higher the entropy, the exponentially harder it is for a hacker's computer to guess.
The Math: The calculation is based on the size of the "pool" of characters you use (e.g., lowercase letters = 26, uppercase = 26, numbers = 10, symbols = 32) and the total length of the password. A short password with many symbols can have the exact same entropy as a very long password containing only lowercase letters.
Crack Time Estimation: Based on the entropy score, the tool estimates how long it would take a modern cluster of specialized graphics cards (GPUs) hashing at roughly 100 Billion guesses per second to successfully brute-force the password. A password is only considered "Strong" if the estimated crack time exceeds several centuries.
Frequently asked questions
Is it safe to type my real password here?
While the calculation is performed safely in memory and immediately discarded, it is a universal cybersecurity best practice to never type your exact, real-life master passwords into any random website. Instead, type a password that is highly similar in length and structure to test the algorithm.
Why does a 15-character phrase score higher than a complex 8-character password?
Because mathematics favors length over complexity. An 8-character password like `P@$$w0rd` is easily cracked by modern computers because the total number of permutations is relatively small. A 15-character phrase consisting of random dictionary words (like `correct horse battery staple`) contains vastly more entropy and is computationally impossible to brute-force.
What is the minimum recommended length for a modern password?
Most security experts (including NIST guidelines) now strongly recommend a minimum of 12 to 14 characters for standard passwords, and at least 20 characters for master passwords protecting password managers.
Does this check if my password has been leaked?
This specific tool only calculates mathematical entropy. If you want to check if your password was exposed in a public data breach, you should use our Pwned Password Checker tool, which securely queries the HaveIBeenPwned database using k-anonymity hashing.
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