Custom Password Generator Calculator

Password Policy Form

Random Password Length

This length covers only the random core.

How Many Passwords

Generate up to 25 passwords per run.

Guesses Per Second

Used for average crack time estimation.

Prefix

Optional fixed text added before each result.

Suffix

Optional fixed text added after each result.

Custom Include Characters

Extra characters merged into the allowed pool.

Custom Exclude Characters

Any matching character is removed everywhere.

Lowercase

Uppercase

Digits

Symbols

Exclude Similar Characters

Require Every Selected Group

Allow Repeated Characters

Plotly Graph

This line graph shows how entropy grows as the random length increases under your current policy.

Current pool size: 79

Example Data Table

Profile	Random Length	Pool Size	Repeat Rule	Entropy Bits	Average Crack View	Example Output
Application Login	16	67	Allowed	97.11	Very long at 10 billion guesses each second	Y7@pL2!mQ4#tR8$s
Admin Console	20	67	Allowed	121.38	Extremely long under fast offline attack models	K9$uN4!xV7@hD2#qM5%w
Device Key	24	57	Blocked	132.48	Massive search space with no repeated characters	Z8!fR2#nT5@wQ6$sJ7%kL9&m

Formula Used

Allowed Pool Size (N): Count every unique character still available after all selected groups, exclusions, and custom include characters are merged.

Combinations with repeats allowed: N^L, where L is the random password length.

Combinations with repeats blocked: N × (N - 1) × (N - 2) ... × (N - L + 1).

Entropy Bits: log2(Combinations). Higher entropy means more unpredictability.

Strength Score: min(100, round(Entropy Bits)).

Average Crack Time: Combinations ÷ 2 ÷ guesses_per_second. The divisor of two reflects the average search position.

Important note: fixed prefixes and suffixes are not counted as random entropy because reusable fixed text can weaken real deployments.

How to Use This Calculator

Set the random password length and choose how many passwords you want.
Enable lowercase, uppercase, digits, symbols, or custom characters.
Remove confusing characters with the exclude options when readability matters.
Choose whether every selected group must appear at least once.
Disable repeated characters if your policy demands unique positions.
Enter a guess rate to model how fast an attacker may test guesses.
Press Generate Passwords to display results above the form.
Export the generated table to CSV or PDF for audits, provisioning logs, or team review.

FAQs

1) Why does entropy matter?

Entropy estimates unpredictability. Higher entropy means more possible guesses, which generally increases resistance to brute force attacks. It is a mathematical guide, not a guarantee against weak storage or phishing.

2) Does adding symbols always make passwords stronger?

Usually yes, because symbols enlarge the allowed pool. Strength rises most when symbols are added to a longer random password instead of replacing good length with a short but complex pattern.

3) Should I block repeated characters?

Blocking repeats can satisfy policy rules, but it also changes the combination model. In most cases, longer length matters more than removing repeats. Use the option only when your environment requires it.

4) Why are prefixes and suffixes excluded from entropy?

A reusable fixed prefix or suffix can become predictable. This calculator treats only the random core as true entropy so the reported strength remains conservative and easier to compare.

5) What guess rate should I enter?

Use a rate that matches your threat model. Online logins may allow very few guesses, while offline attacks against leaked hashes can be dramatically faster. The input helps you compare scenarios.

6) Are generated passwords cryptographically secure?

This file uses random_int(), which draws from a cryptographically secure source in modern environments. Security still depends on safe transport, storage, and avoiding exposure in browser history or screenshots.

7) Why might my selected groups cause an error?

Errors appear when exclusions remove every character from a chosen group, or when length becomes too short for every required group. The tool validates these cases before generation.

8) When should I export the results?

Export when you need a review sheet, temporary provisioning record, or audit artifact. Handle exported files carefully because they may contain live credentials and should never stay in shared storage.