Password Entropy Calculator
Entropy bits and crack time.
Enter your values
Enter the password length you are working with.
Choose one of: Lowercase only, Upper and lower, Alphanumeric, All printable ASCII.
Enter the guesses per second you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Entropy
- 91.8 bits
- Time to crack
- 667497127 years
- Combinations
- 4.205e+27
- Rating
- Strong
Quick answer
Password entropy measures unpredictability in bits; each extra bit doubles the search space.
Entropy = length × log2(character set)
At a glance
| What it does | Entropy bits and crack time. |
|---|---|
| Category | Technology |
| Inputs needed | Password length, Character set, Guesses per second |
| Main output | Entropy |
| Formula | Entropy = length × log2(character set) |
| Cost | Free — no sign-up, no download |
How to use the Password Entropy Calculator
- 1Enter the password length.
- 2Choose the character set used.
- 3Adjust attacker guess rate for your threat model.
Inputs explained
- Password length
- Enter the password length you are working with.
- Character set
- Choose one of: Lowercase only, Upper and lower, Alphanumeric, All printable ASCII.
- Guesses per second
- Enter the guesses per second you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Password length14
- Character setAll printable ASCII
- Guesses per second1e11
Results
- Entropy91.8 bits
- Time to crack667497127 years
- Combinations4.205e+27
- RatingStrong
Frequently asked questions
How many bits is enough?
80+ bits resists offline attacks for the foreseeable future.
Are passphrases better?
Yes — four random words beat a short complex password.
What do I need to enter into the Password Entropy Calculator?
Just 3 values: password length, character set, guesses per second. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Password Entropy Calculator work out the answer?
Password entropy measures unpredictability in bits; each extra bit doubles the search space. It applies the formula Entropy = length × log2(character set) and shows the working so you can check each step by hand.
Is the Password Entropy Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.