utility calculator

Password Generator

Generate secure passwords with custom rules.

Formula Verified by Dr. Arthur Pendelton, PhD

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Password type

Password length

Seed

Results

Generated password

zj!K%^F^aEgXK5

Length14

Character pool65

Bookmark this password tool

Keep this tool handy for creating safe passwords during account registration or security audits.

Formula

Deterministic password generation

Each character is selected from the chosen character pool using a repeatable seeded random sequence

A seed produces the same password pattern for the same settings, which helps with reproducible testing and examples.

Step by step

How the calculation works

1Choose the password complexity level.
2Set the password length.
3Use a seed to generate a repeatable example.
4Build the password one character at a time from the selected character pool.

Example

Example password output

A 14-character strong password uses letters, numbers, and symbols from a larger character pool than the standard and numeric modes.

Related guides

Learn more about this calculation

Guide

Password Entropy Guide: Length, Character Pools, and the Limits of Complexity Rules

Understand how password entropy is estimated from length and character-pool size, how the current DTC password generator behaves, and why secure password policy depends more on length and uniqueness than on arbitrary complexity rituals.

Guide

Random Number Generation Guide: Seeded PRNGs, True Randomness, and Safe Use Cases

Learn the difference between deterministic seeded generators, browser pseudo-random functions, and cryptographically strong randomness so you can use the right tool for the job.

How to understand and use this calculator

Determining Password Strength and Entropy

A secure password must be resistant to automated cracking attempts. We measure password strength mathematically using Bits of Entropy, which quantifies the randomness or unpredictability of the character string.

The entropy formula is:

$$E = L \times \log_2(R)$$

Where:

* $E$ is the password entropy in bits.

* $L$ is the length of the password (character count).

* $R$ is the pool size of available characters (charset size).

Each additional character increases entropy linearly, while expanding the character pool (adding numbers, uppercase letters, and symbols) increases it logarithmically. Length is the primary driver of brute-force security.

Brute-Force Attack Timelines

Brute-force attacks use high-speed computing clusters to guess password combinations systematically. A password with 30 bits of entropy can be cracked in seconds. A strong password targeting 80+ bits of entropy would require millions of years to crack with current consumer computing power.

To protect credentials, use a minimum length of 12 to 16 characters and a diverse character pool.

Deterministic Password Generation

This tool generates passwords deterministically from a Seed Value. Deterministic generation means that the same seed, length, and character settings will always produce the exact same password. This is highly useful for developers managing repeatable environment setups, testing local encryption profiles, or validating encryption keys.

Related concepts

Brute-force attack

A trial-and-error method used by application programs to guess login credentials or encryption keys.

Entropy

A measure of the randomness or unpredictability of a password, commonly measured in bits.

Password Salt

Random data added to a password input before hashing to secure it against precomputed table attacks.

Frequently Asked Questions

What makes a password strong?+

Password strength is determined by length and character diversity. Standard passwords use letters and numbers, while strong passwords add special characters, expanding the character pool and raising entropy.

What is a seed in password generation?+

A seed is an input value used to start the random sequence. The same seed, length, and mode will always produce the exact same password, allowing reproducible testing.

What is a brute-force attack?+

A trial-and-error method used by application programs to guess login credentials or encryption keys by testing every possible combination.

What is bits of entropy?+

A mathematical measure of password strength. Higher entropy (measured in bits) indicates a password is more random and harder for computers to guess.

How does length compare to character diversity for strength?+

Length is more effective at raising entropy. A 16-character password using only lowercase letters is mathematically stronger than an 8-character password using letters, numbers, and symbols.

What is a password salt?+

A salt is random data added to a password before hashing. It protects stored passwords against database leak attacks like rainbow tables.

Should I reuse my master seed password?+

No. Never reuse seeds or master passwords across different production accounts or environments, as a leak in one compromises all.

What is the recommended entropy for a safe password?+

A minimum of 60 bits of entropy is recommended for basic accounts, and 80+ bits for high-security accounts or master passwords.

Does the seed value get sent to any server?+

No. All deterministic calculations are processed locally inside your browser, ensuring your seeds never leave your local device.

How do password managers generate passwords?+

Password managers use cryptographically secure pseudo-random number generators (CSPRNGs) to generate non-deterministic, highly random passwords.

How to understand and use this calculator

Determining Password Strength and Entropy

The entropy formula is:

$$E = L \times \log_2(R)$$

Where:

* $E$ is the password entropy in bits.

* $L$ is the length of the password (character count).

* $R$ is the pool size of available characters (charset size).

Brute-Force Attack Timelines

To protect credentials, use a minimum length of 12 to 16 characters and a diverse character pool.

Deterministic Password Generation

Related concepts

Brute-force attack

A trial-and-error method used by application programs to guess login credentials or encryption keys.

Entropy

A measure of the randomness or unpredictability of a password, commonly measured in bits.

Password Salt

Random data added to a password input before hashing to secure it against precomputed table attacks.

Frequently Asked Questions

What makes a password strong?+

What is a seed in password generation?+

A seed is an input value used to start the random sequence. The same seed, length, and mode will always produce the exact same password, allowing reproducible testing.

What is a brute-force attack?+

A trial-and-error method used by application programs to guess login credentials or encryption keys by testing every possible combination.

What is bits of entropy?+

A mathematical measure of password strength. Higher entropy (measured in bits) indicates a password is more random and harder for computers to guess.

How does length compare to character diversity for strength?+

Length is more effective at raising entropy. A 16-character password using only lowercase letters is mathematically stronger than an 8-character password using letters, numbers, and symbols.

What is a password salt?+

A salt is random data added to a password before hashing. It protects stored passwords against database leak attacks like rainbow tables.

Should I reuse my master seed password?+

No. Never reuse seeds or master passwords across different production accounts or environments, as a leak in one compromises all.

What is the recommended entropy for a safe password?+

A minimum of 60 bits of entropy is recommended for basic accounts, and 80+ bits for high-security accounts or master passwords.

Does the seed value get sent to any server?+

No. All deterministic calculations are processed locally inside your browser, ensuring your seeds never leave your local device.

How do password managers generate passwords?+

Password managers use cryptographically secure pseudo-random number generators (CSPRNGs) to generate non-deterministic, highly random passwords.

Password Generator

Inputs

Results

Bookmark this password tool

Deterministic password generation

How the calculation works

Example password output

Learn more about this calculation

Password Entropy Guide: Length, Character Pools, and the Limits of Complexity Rules

Random Number Generation Guide: Seeded PRNGs, True Randomness, and Safe Use Cases

Password Generator

Inputs

Results

Bookmark this password tool

Key output metrics

Pool Size Comparison

Strength / Entropy Analysis

How to understand and use this calculator

Determining Password Strength and Entropy

Brute-Force Attack Timelines

Deterministic Password Generation

Related concepts

Frequently Asked Questions

Deterministic password generation

How the calculation works

Example password output

Learn more about this calculation

Password Entropy Guide: Length, Character Pools, and the Limits of Complexity Rules

Random Number Generation Guide: Seeded PRNGs, True Randomness, and Safe Use Cases

Key output metrics

Pool Size Comparison

Strength / Entropy Analysis

How to understand and use this calculator

Determining Password Strength and Entropy

Brute-Force Attack Timelines

Deterministic Password Generation

Related concepts

Frequently Asked Questions