This calculator uses secure random selection and simple combinatorics. It estimates password combinations, entropy, and strength labels from your chosen character pool and length.
Password Generator Inputs
Plotly Entropy Graph
This chart compares estimated entropy across nearby password lengths.
Example Data Table
| Example | Length | Pool Size | Approx. Combinations | Entropy | Label |
|---|---|---|---|---|---|
| Letters and numbers | 10 | 62 | 8.393 × 10^17 | 59.54 bits | Fair |
| Longer alphanumeric set | 12 | 62 | 3.226 × 10^21 | 71.45 bits | Strong |
| Wide set with exclusions | 16 | 72 | 5.216 × 10^29 | 98.72 bits | Very Strong |
| Long password with full mix | 20 | 88 | 7.756 × 10^38 | 129.19 bits | Excellent |
Formula Used
Character Pool Size: N = total unique characters from all selected sets.
Total Combinations: C = NL
Entropy Estimate: H = L × log2(N)
Where: L = password length, N = pool size, H = bits of entropy.
This calculator treats the password space as a combinatorics problem. Larger pools and longer lengths increase the search space rapidly.
When you require at least one symbol type or avoid repeated characters, the exact count changes slightly. The displayed values remain useful for practical comparison.
In simple terms, more choices per position and more positions together produce much stronger passwords.
How to Use This Calculator
- Choose a password length that fits your security goal.
- Select the character sets you want included.
- Enable exclusions for ambiguous or repeated characters if needed.
- Enter how many passwords you want generated.
- Click Generate Passwords to create results.
- Review the entropy, combinations, and strength labels.
- Copy one password or export the whole set to CSV or PDF.
- Use the chart to see how length changes the estimated strength.
FAQs
1) Why does password length matter so much?
Every added character multiplies the total combinations. That growth is exponential, so even a small increase in length raises search difficulty sharply.
2) What does entropy mean here?
Entropy is a mathematical estimate of unpredictability. Higher bits usually mean a larger search space and a harder password to guess or brute-force.
3) Are symbols always necessary?
Not always, but they usually increase pool size and entropy. A longer password without symbols can still be strong if its length is high enough.
4) Why exclude ambiguous characters?
Excluding lookalike characters helps when you must read or type passwords manually. It slightly lowers the pool size but improves usability and accuracy.
5) Does avoiding repeats make passwords stronger?
It can improve visual variety, but it also reduces the exact search space. Many users choose it mainly to avoid accidental patterns or repeated confusion.
6) Is one generated password enough?
One can be enough, but generating several options helps you choose a format you can store safely. Always keep passwords unique across accounts.
7) Can this calculator guarantee real-world security?
No calculator can guarantee full safety. Security also depends on storage, phishing resistance, device hygiene, and whether a password is reused elsewhere.
8) What is the best practical setting?
A long password with mixed character sets is usually a strong default. Aim for uniqueness first, then choose a length your systems and password manager support.