Use our free Password Entropy Calculator to check how strong your password or passphrase is in bits of entropy. Learn why entropy matters for security and how to create uncrackable passwords.

Try the Calculator Now!

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🔐 What Is Password Entropy?

Password entropy measures the unpredictability of a password in bits. The higher the entropy, the harder it is for hackers to crack your password using brute-force attacks.

• Low entropy (0-28 bits): Easily cracked in seconds.
• Moderate entropy (36-59 bits): Takes days to years to break.
• High entropy (60+ bits): Virtually uncrackable in a human lifetime.

Our Password Entropy Calculator helps you evaluate your password strength instantly.

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📊 How Does the Password Entropy Calculator Work?

Our calculator evaluates:
✅ Character variety (uppercase, lowercase, numbers, symbols)
✅ Password length (longer = stronger)
✅ Total possible combinations (exponential difficulty for attackers)

The formula used:

Entropy (bits) = log₂(Character Pool Size ^ Password Length)

Example:

• A 12-character password with uppercase + lowercase + numbers + symbols (pool size = 94) has ~78 bits of entropy—extremely strong!

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🔢 What’s a Good Password Entropy?

Entropy (bits)	Strength	Time to Crack*
< 28	Very Weak	Seconds
29-35	Weak	Minutes to hours
36-59	Moderate	Days to years
60-127	Strong	Centuries
128+	Very Strong	Longer than the universe’s age

Assumes an offline attack at 1 trillion guesses per second.

👉 Want a high-entropy password? Try our Strong Password Generator.

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🚀 How to Increase Your Password’s Entropy

1. Use Longer Passwords
   • A 16-character password is exponentially stronger than an 8-character one.
2. Mix Character Types
   • Combine uppercase (A-Z), lowercase (a-z), numbers (0-9), and symbols (!@#).
3. Avoid Common Words & Patterns
   • “Password123” has low entropy despite length.
4. Consider Passphrases
   • “CorrectHorseBatteryStaple” is long and memorable but still needs complexity.
   • Generate one with our Passphrase Generator.
5. Use a Password Manager
   • Tools like Bitwarden or 1Password create & store high-entropy passwords.

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🔍 Why Is Password Entropy Important?

• Prevents Brute-Force Attacks – Hackers use automated tools to guess passwords. High entropy slows them down.
• Protects Against Data Breaches – Weak passwords are easily cracked from leaked databases.
• Essential for Online Security – Banking, emails, and social media need strong passwords.

💡 Pro Tip: Always enable Two-Factor Authentication (2FA) for extra security!

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📉 Common Low-Entropy Password Mistakes

❌ Short passwords (e.g., “qwerty”, “123456”)
❌ Repeating characters (e.g., “aaaaaa”)
❌ Dictionary words (e.g., “sunshine”, “dragon”)
❌ Personal info (e.g., “John1985”, “PetName123”)

👉 Test your password now with our calculator

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❓ Frequently Asked Questions (FAQ)

1. What is a good password entropy value?

Aim for at least 60 bits for strong security. Passwords with 128+ bits are considered extremely secure and nearly uncrackable with current technology.

2. Does a longer password always mean higher entropy?

Not necessarily. A long password like “aaaaaaaa” has low entropy because it lacks complexity. Length + character variety maximizes entropy.

3. How is password entropy calculated?

The formula is:

Entropy (bits) = log₂(Character Pool Size ^ Password Length)

For example:

• A 10-character password with lowercase + uppercase + numbers + symbols (pool size = 94) has ~65 bits of entropy.

4. Is a high-entropy password hard to remember?

Not if you use passphrases (e.g., “BlueCoffeeMug$729!”) or a password manager.

5. Can two different passwords have the same entropy?

Yes, if they have the same length and character variety, they can have identical entropy values even if the actual passwords differ.

6. How often should I check my password entropy?

Whenever you:

• Create a new password
• Update an existing one
• Suspect a data breach

7. Are passphrases better than random passwords?

They can be if:

• Long enough (4+ random words)
• Include numbers/symbols (e.g., “CorrectHorseBatteryStaple42!”)

Try our Passphrase Generator for secure, memorable passphrases.

8. Does entropy guarantee password security?

No—entropy measures resistance to brute-force attacks, but:

• Never reuse passwords
• Enable 2FA
• Beware of phishing

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🔗 Further Reading

• How to Create a Strong Password
• Password vs. Passphrase: Which Is Better?
• Best Password Managers in 2024 (External)

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🎯 Final Thoughts

A high-entropy password is your first defense against cyberattacks. Use our Password Entropy Calculator to check your current passwords and generate stronger ones with our Password Generator.

🔒 Stay secure, and keep your data protected!