# Secure Password Generator

- **URL:** https://codeasystem.com/calculators/developer/password-generator/
- **Category:** developer
- **Description:** Build random passwords from selectable character classes with guaranteed coverage, ambiguity filtering and entropy estimates.
- **Primary output:** Password recipe: 16-character password with lower+upper+digits

## Inputs
- Length (name: `length`, type: number, example: 16)
- Lowercase a–z (name: `lowercase`, type: select)
- Uppercase A–Z (name: `uppercase`, type: select)
- Digits 0–9 (name: `digits`, type: select)
- Symbols !@#$ (name: `symbols`, type: select)
- Ambiguous chars (l 1 I O 0) (name: `excludeAmbiguous`, type: select)

## Outputs
- Password recipe: 16-character password with lower+upper+digits
- Your password: AHsdI7CWzwVKB0HQ
- Character pool size: 62 possible characters
- Entropy estimate: 95.3 bits
- Strength verdict: strong

## Formula / methodology
```
entropy bits = length × log₂(pool size); pool = union of enabled character classes
```

One character is drawn from every enabled class first; guaranteeing each policy requirement is met; then the remaining slots fill uniformly from the combined pool and the whole sequence is shuffled so position never leaks which slot held the guarantee draw.

Entropy is estimated as length × log₂ of the combined pool size, with a verdict band translating bits into practical strength terms. Excluding visually ambiguous characters (l, 1, I, O, 0) shrinks the pool slightly and the estimate reflects that honestly.

## Assumptions & limitations
- Randomness sourced from the platform CSPRNG.
- Entropy math assumes uniform random selection over the pool.
- Policies requiring specific placement rules (digit-first etc.) are not modeled.

## How to use
1. **Match the site policy**; Toggle classes until the recipe satisfies whatever rules the signup form enforces.
2. **Consider ambiguous chars**; Exclude l/1/I/O/0 when passwords will be read aloud or transcribed by hand.
3. **Copy and store it**; Paste straight into your password manager; never reuse it elsewhere.

## Example
A 16-character recipe over lower+upper+digits pools 62 possible characters; roughly 95 bits of entropy, comfortably strong for any login.

Result for these inputs:

```
Password recipe: 16-character password with lower+upper+digits
```

## About this calculator
### Length beats cleverness

Each added character multiplies search space by the pool size; going from 12 to 16 characters over a 62-symbol pool adds roughly 24 bits of entropy, dwarfing any symbol-substitution trickery. When in doubt, make it longer, not weirder.

### Why guaranteed-class draws then shuffle

Pure rejection sampling (“regenerate until it contains a digit”) wastes iterations; drawing one per class then shuffling satisfies constraints deterministically while keeping the remainder uniform. Shuffling ensures the guaranteed draws are indistinguishable by position.

## FAQs
### Are generated passwords stored or transmitted?

No. Generation happens locally in your browser with the platform’s secure random source; nothing is logged or sent anywhere.

### Why does the summary differ from the actual password?

Passwords are freshly randomized each run; the headline describes the deterministic recipe (length and classes) while the concrete secret sits in the results panel.

### Is excluding ambiguous characters safe?

It removes five characters from consideration, trimming entropy marginally; a fine trade when humans must type the password accurately.

### Should symbols always be enabled?

Only if the target system accepts them and you will paste rather than type. Length contributes far more strength than symbol inclusion.

## Related calculators
- [Password Strength Calculator](https://codeasystem.com/calculators/developer/password-strength-calculator/)
- [SHA Hash Generator](https://codeasystem.com/calculators/developer/hash-generator/)
- [UUID v4 Generator](https://codeasystem.com/calculators/developer/uuid-generator/)

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Last updated: 2026-08-23 · Version: 1.0.0 · [HTML version](https://codeasystem.com/calculators/developer/password-generator/)