How the Password Generator works

This Password Generator uses the browser’s cryptographic random-number function to select characters from the enabled sets. The generated value is not submitted to HomeCalculation. A password can include lowercase and uppercase letters, digits and symbols. Enabling more character types expands the possible combinations, while increasing length has the largest practical effect on resistance to guessing.

The ambiguous-character option removes characters that are easy to confuse in some fonts, such as uppercase I, lowercase l, the number 1, uppercase O and the number 0. Removing them slightly reduces the character pool but can be useful when a password must be typed manually.

Password entropy formula

The estimated entropy is H = L × log₂(N), where L is password length and N is the number of possible characters in the selected pool. For example, a 20-character password drawn uniformly from 72 possible characters has about 123 bits of theoretical entropy. This estimate assumes every character is selected independently and uniformly.

Entropy is a mathematical estimate, not a guarantee that an account is secure. Security also depends on the website’s storage practices, rate limiting, multi-factor authentication and whether the password has been exposed elsewhere.

Worked example

Suppose you choose 20 characters and enable lowercase, uppercase, numbers and symbols. The generator combines those character sets and obtains random values from the browser. Each random value selects one character. The result is evaluated by length and estimated entropy. If the password contains every selected category, the tool displays a stronger rating than a shorter password drawn from a smaller pool.

How long should a password be?

Longer passwords are generally more resistant to automated guessing. Sixteen or more randomly generated characters is a practical starting point for many accounts, but service requirements may differ. When a website permits passkeys, security keys or multi-factor authentication, use those protections as well. A password manager can generate and store a different long password for every account.

Random passwords versus memorable passphrases

A random password is suitable when a password manager will store it. A passphrase made from several randomly selected words may be easier to enter manually. Do not create a passphrase from predictable personal facts, quotations or a simple pattern. Human-created substitutions such as replacing “a” with “@” are widely anticipated by password-cracking rules.

Safe storage and export

The Copy button places the password on the clipboard, where other software may sometimes read it. Paste it promptly into the intended password field or password manager and then clear the clipboard when appropriate. The optional downloads are provided for compatibility, but an unencrypted PDF or CSV file can expose the password. Prefer a reputable password manager and delete insecure exports after use.

Current digital identity guidance is available from the NIST Digital Identity Guidelines. Follow the requirements of the service where the password will be used.

Frequently asked questions

Does HomeCalculation store the generated password?

No. The generator runs in your browser and does not send the result to the website’s server.

Why use cryptographic randomness?

Ordinary pseudo-random functions are designed for simulations, not secrets. The browser cryptography interface is intended to provide stronger unpredictable random values.

Should every character type be required?

Some services require categories. Length and uniqueness matter more than decorative complexity, but selecting multiple sets helps satisfy common rules and expands the pool.

Can I reuse a strong password?

No. Reuse allows one breached service to endanger other accounts. Generate a unique password for every account.

Is the strength rating exact?

No. It is an educational estimate based mainly on length, pool size and selection. Real attacks also exploit leaked passwords, patterns and service-specific weaknesses.

The Password Generator is free, private, and designed for quick local use. Use the Password Generator whenever you need a unique credential rather than adapting an old password.