⚡ Quick Answer
A strong password has: 12+ characters, uppercase and lowercase letters, numbers, and symbols. Example strong password: 'Tr0ub4dor&3'. Example weak password: 'password123'. A 12-character random password with mixed characters would take computers billions of years to crack. Never reuse passwords across sites!
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🔒 Password Strength Checker

Check how strong your password is instantly. Get a strength score, time-to-crack estimate, and specific improvement suggestions. Understand what makes passwords secure.

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🔒 Your password is never sent to any server. All checking happens in your browser only.
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✅ Trusted Tool
The 365tool.net Password Strength Checker runs 100% in your browser — your password is NEVER sent to any server or stored anywhere. Free security tool for everyone. No sign-up needed.

🤔 How Does This Work?

The Password Strength Checker analyses multiple factors:

  • Length score (most important): 12+ chars = good, 16+ = excellent
  • Character variety: lowercase, uppercase, numbers, symbols
  • Pattern detection: repeated chars, sequences, keyboard patterns
  • Common password check: known weak passwords flagged immediately
  • Entropy calculation: estimate of bits of randomness

All analysis runs entirely in your browser. Your password is never transmitted anywhere.

❓ Frequently Asked Questions

What makes a password strong?
Length (most important!): 12+ characters. Variety: uppercase, lowercase, numbers, symbols. Randomness: no dictionary words, no personal info. Uniqueness: never reused across sites. A 20-character random password is exponentially stronger than a 10-character one. Length matters more than complexity.
How long would it take to crack my password?
A 6-character lowercase password: less than 1 second. An 8-character mixed password: 8 hours. A 12-character mixed password: 34,000 years. A 16-character random password: longer than the universe's age. Each character added multiplies crack time by the character set size (62 for alphanumeric, 95 with symbols).
What are the worst passwords?
Annual lists consistently show: password, 123456, password123, qwerty, abc123, letmein, admin, welcome, monkey, dragon. These are cracked in milliseconds. Anything with your name, birthday, favourite sports team, or pet's name is weak — these are the first things hackers try.
Should I use a password manager?
Yes! Password managers (Bitwarden, 1Password, LastPass) generate and store unique strong passwords for every site. You only need to remember one master password. This is the single best security improvement most people can make. Many are free. Never reuse passwords.
What is two-factor authentication (2FA)?
2FA adds a second verification step beyond password: a code sent to your phone, an authenticator app code, or a hardware key. Even if someone knows your password, they cannot log in without your second factor. Enable 2FA on email, banking, and social media accounts immediately.
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❓ FAQ
What makes a password strong?
Length (most important!): 12+ characters. Variety: uppercase, lowercase, numbers, symbols. Randomness: no dictionary words, no personal info. Uniqueness: never reused across sites. A 20-character random password is exponentially stronger than a 10-character one. Length matters more than complexity.
How long would it take to crack my password?
A 6-character lowercase password: less than 1 second. An 8-character mixed password: 8 hours. A 12-character mixed password: 34,000 years. A 16-character random password: longer than the universe's age. Each character added multiplies crack time by the character set size (62 for alphanumeric, 95 with symbols).
What are the worst passwords?
Annual lists consistently show: password, 123456, password123, qwerty, abc123, letmein, admin, welcome, monkey, dragon. These are cracked in milliseconds. Anything with your name, birthday, favourite sports team, or pet's name is weak — these are the first things hackers try.
Should I use a password manager?
Yes! Password managers (Bitwarden, 1Password, LastPass) generate and store unique strong passwords for every site. You only need to remember one master password. This is the single best security improvement most people can make. Many are free. Never reuse passwords.
What is two-factor authentication (2FA)?
2FA adds a second verification step beyond password: a code sent to your phone, an authenticator app code, or a hardware key. Even if someone knows your password, they cannot log in without your second factor. Enable 2FA on email, banking, and social media accounts immediately.