Password Generator
Generate strong, random passwords with customizable length, character types, and strength analysis.
A password generator creates cryptographically random passwords with configurable length, character sets, and complexity requirements.
Examples
16-character full charset
8-character lowercase only
Frequently Asked Questions
What is password entropy?
How is crack time estimated?
Quick Tips
- •Use at least 12 characters for good security.
- •Include all character types for maximum entropy.
- •Never reuse passwords across different accounts.
- •Consider using a password manager to store generated passwords.
A password generator creates cryptographically random passwords with configurable length, character sets, and complexity requirements.
How to Use This Calculator
Set the desired password length, choose which character types to include, and specify how many passwords to generate. The calculator will produce random passwords and show their estimated strength.
Understanding the Formula
Password Entropy (bits) = Length x log2(Charset Size). Higher entropy means a stronger password. A charset of 95 characters (upper + lower + digits + symbols) at length 16 yields about 105 bits of entropy.
Examples
16-character full charset
Using uppercase, lowercase, numbers, and symbols (95 chars): Entropy = 16 x log2(95) = 105 bits. Estimated crack time with 10 billion guesses/sec: trillions of years.
8-character lowercase only
Using only lowercase (26 chars): Entropy = 8 x log2(26) = 37.6 bits. This is weak and could be cracked in hours.
Frequently Asked Questions
What is password entropy?
Entropy measures the randomness (unpredictability) of a password in bits. Each bit doubles the number of possible combinations. A password with 80+ bits of entropy is considered strong against brute-force attacks.
How is crack time estimated?
Crack time assumes an attacker can try 10 billion passwords per second (a powerful GPU cluster). The estimate is the average time to find the password by brute force, which is half the total keyspace divided by the guess rate.
Assumptions & Limitations
- Randomness relies on the Web Crypto API (crypto.getRandomValues), which is cryptographically secure in modern browsers.
- Crack time estimates assume brute-force attacks at 10 billion guesses per second and do not account for dictionary or pattern-based attacks.
- Entropy calculation assumes every character is independently and uniformly chosen from the full charset.