Comprehensive Calculator Guide
This calculator gives the number of possible passwords, the strength in bits and the expected time to crack by brute force, from the character set and length. A random 8-character alphanumeric password has 47.6 bits and falls in about 3 hours at 10 billion guesses a second.
Length wins
Combinations = N^L; bits = L × log2(N); expected time = N^L ÷ 2 ÷ rate. Four more characters do far more than adding symbols. All this assumes truly random passwords.
How to Use
- Pick the character set.
- Enter the length and, optionally, the guess rate.
- Press “Check strength” to see bits and crack time.
Formula Used
Combinations = N^L | Bits = L × log2(N) | Time = N^L ÷ 2 ÷ rate
Practical Examples
- Example 1
- 8 alphanumeric: 47.6 bits, ~3 hours.
- Example 2
- 6-digit PIN: 19.9 bits, under a second offline.
Important Tips
- Use 12+ characters.
- Never reuse passwords.
- Use a generator and a manager.
Common Mistakes to Avoid
- Predictable substitutions.
- Birthdays and names.
- Applying this to non-random passwords.
Frequently Asked Questions
- How many bits?
- 60+ strong, 128 very strong.
- Longer or more symbols?
- Longer.
- Why is a phone PIN safe?
- The phone limits attempts.