Password Generator
Use this free Password Generator to calculate your Strong passwords instantly and accurately.
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Your password
What is a Password Generator?
A Password Generator creates strong, random passwords that are resistant to guessing and brute-force attacks. It uses cryptographically secure random number generation to select characters from a configurable pool including uppercase letters, lowercase letters, digits, and symbols. Strong passwords protect your online accounts from unauthorized access by making it computationally infeasible to guess the password.
How to calculate password strength manually (the formula)
Password entropy (in bits) is calculated as: entropy = log&sub2;(N^L) where N is the size of the character set and L is the password length. For a 16-character password using all 95 ASCII printable characters: entropy = log&sub2;(95^16) ≈ 105 bits. Each additional character multiplies the search space by N. A password with 128+ bits of entropy is considered secure against all current brute-force attacks.
Example calculation
A generated password kG7#xP2!mQ9&zR5$ (16 characters, mixed types) has character set size = 95. Entropy = 16 × log&sub2;(95) ≈ 105 bits. A brute-force attack trying 1 trillion passwords per second would take 2^105 / 10^12 ≈ 4 × 10^19 seconds, far longer than the age of the universe. Without symbols and digits, the same length using only mixed-case letters gives 52^16 ≈ 91 bits — still strong, but significantly weaker.
Common mistakes
- Using personal information — Birthdays, names, and pet names can be guessed through social engineering or data mining.
- Reusing passwords across sites — If one site is breached, all accounts sharing that password become vulnerable.
- Choosing shorter passwords for convenience — Every character removed cuts the search space by 95×. A 12-character password is 95^4 (81 billion) times weaker than a 16-character one.
Frequently asked questions
How is a random password generated?
A cryptographically random character is selected from the pool of chosen character types for each position.
What makes a password strong?
Length (16+ characters), diversity (uppercase, lowercase, digits, symbols), and randomness prevent brute-force attacks.
Should I use symbols in my password?
Yes, symbols expand the character set, exponentially increasing the number of possible combinations.
How many characters should a password be?
At least 12; 16 or more is recommended for critical accounts.
Is this password generator secure?
Yes, it uses crypto.getRandomValues() for cryptographically secure random numbers.
Can I control which character types are included?
Yes, you can toggle uppercase, lowercase, digits, and symbols independently.