Password Generator
Generates random passwords from the character sets you choose, with the entropy in bits.
Results
What this tool does
Length beats cleverness. A sixteen-character password drawn from all four character sets carries about a hundred bits of entropy, which is far past anything that can be brute-forced; the same password with the symbols dropped loses about ten of those bits, and dropping to eight characters halves the number outright. The entropy figure is the honest measure — it counts how much genuine randomness went in, which is not the same as how complicated the result looks.
Formula
entropy = length x log2(alphabet size)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
length | Password length | — |
count | How many | — |
use_lower | Lower case a-z | — |
use_upper | Upper case A-Z | — |
use_digits | Digits 0-9 | — |
use_symbols | Symbols | — |
seed | Seed | — |
OUT | Passwords | — |
EN | Entropy | bits |
PL | Characters to choose from | — |
Worked example
- Password length16
- How many5
- Lower case a-z1
- Upper case A-Z1
- Digits 0-91
- Symbols1
- Seed2026
- PasswordsIxYVlqZ8wdfVDinz E-Qapu7@?6vuFvY$ w-gdz64E^ZVBc~n^ #uLn_T&6TJM76RZ^ Cang@=nmKSv@+b^V
- Entropy99.97 bits
- Characters to choose from76
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.
Frequently asked questions
Is a password generated from a seed safe to use?
Treat it as convenient, not as cryptographically strong. The seed is drawn from your browser's secure random source when you press Again, but the generator that expands it is a small statistical one, not a cryptographic one, and anyone who learns the seed can reproduce the password. For anything that matters, use the generator built into your password manager, and never write the seed down beside the password.