Password Generator

How to use this calculator

1. Enter or choose length.
2. Enter or choose lower case (a–z).
3. Enter or choose upper case (A–Z).
4. Enter or choose digits (0–9).
5. Enter or choose symbols (!@#…).
6. The password updates as you type. Use Copy result or Share to keep it.

Method

Entropy = log₂(number of possible passwords). With a pool of N characters and length L this is about L × log₂ N; requiring one of each chosen type is counted exactly by inclusion–exclusion.

N

characters available (94 with all four types)

L

password length

Worked example

1. Pool: 26 lower + 26 upper + 10 digits + 32 symbols = 94 characters.
2. Without restrictions: 16 × log₂ 94 = 16 × 6.555 = 104.9 bits.
3. Requiring at least one of each type removes a small share of combinations, leaving 104.6 bits.

A 16-character password using all 94 printable ASCII characters has about 104.6 bits of entropy.

What the result means

Each extra bit doubles the number of guesses an attacker needs. Around 80 bits is beyond realistic brute force for a random password; use a password manager so every account gets its own.

Assumptions and limits

• Characters are chosen with the Web Crypto API (crypto.getRandomValues) without modulo bias.
• Entropy applies only because the password is random; it says nothing about passwords chosen by people.
• Some sites reject certain symbols or long passwords; switch symbols off or shorten if needed.