Password Generator
Generate secure passwords with strength analysis
Generate cryptographically strong passwords instantly. Choose your length, character types, and get a password with entropy analysis and crack-time estimates. Also check the strength of existing passwords.
A strong password in 2026 should be at least 16 characters with uppercase, lowercase, numbers, and symbols. A 16-character password with all character types has ~105 bits of entropy and would take centuries to crack by brute force.
- Use at least 16 characters for strong security
- Include uppercase, lowercase, numbers, and symbols
- Never reuse passwords across different accounts
- Use a password manager to store complex passwords
- Enable two-factor authentication when available
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Free Password Generator & Strength Checker
How to Use This Password Generator
Click "Generate New Password" to create a random password instantly. Customize it using these options:
- Set the length — 16 characters is the recommended minimum for 2026. Longer is better.
- Choose character types — Enable uppercase, lowercase, numbers, and symbols for maximum entropy.
- Copy and use — Click the Copy button to copy to your clipboard.
- Check existing passwords — Switch to "Check Strength" mode to analyze any password.
What Makes a Password Strong?
Password entropy measures how unpredictable a password is, expressed in bits. Higher entropy = harder to crack.
Entropy = log2(charset_size ^ length)
For example, a 16-character password using uppercase + lowercase + numbers + symbols (94 possible characters) has log2(94^16) = 105 bits of entropy.
| Entropy (bits) | Strength | Crack Time (10B guesses/sec) |
|---|---|---|
| <30 | Weak | Seconds to minutes |
| 30-49 | Fair | Hours to days |
| 50-69 | Good | Years |
| 70-89 | Strong | Thousands of years |
| 90+ | Very Strong | Centuries |
Password Security Best Practices (2026)
- Use a password manager. Tools like 1Password, Bitwarden, or Apple Keychain generate and store unique passwords for every account.
- Enable two-factor authentication (2FA). Even the strongest password can be phished. 2FA adds a second layer.
- Never reuse passwords. If one site gets breached, all accounts with the same password are compromised.
- Avoid personal information. Names, birthdays, pet names, and dictionary words are easily guessed.
- Use passkeys when available. Passkeys (FIDO2/WebAuthn) are phishing-resistant and don't require memorization.
Common Password Lengths Compared
| Length | All Types (94 chars) | Letters+Numbers (62) | Letters Only (52) |
|---|---|---|---|
| 8 chars | 52 bits | 48 bits | 46 bits |
| 12 chars | 79 bits | 71 bits | 68 bits |
| 16 chars | 105 bits | 95 bits | 91 bits |
| 20 chars | 131 bits | 119 bits | 114 bits |
| 24 chars | 157 bits | 143 bits | 137 bits |
Sources
- NIST Special Publication 800-63B — Digital Identity Guidelines
- Entropy formula: Shannon entropy (H = L × log2(R) where L = length, R = charset size)
- Crack time estimate assumes 10 billion guesses per second (modern GPU cluster)
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Preguntas frecuentes
Security experts recommend at least 16 characters for strong passwords in 2026. While 12 characters was once sufficient, advances in GPU-based cracking make longer passwords essential. A 16-character password with mixed character types has approximately 105 bits of entropy and would take centuries to crack by brute force at 10 billion guesses per second.
Password entropy measures how unpredictable a password is, expressed in bits. It is calculated as log2(charset_size ^ length). Higher entropy means more possible combinations, making the password harder to guess. For example, a 16-character password using 94 possible characters (letters, numbers, symbols) has 105 bits of entropy. Generally, 70+ bits is considered strong.
Yes. Humans are predictable in password creation — we use dictionary words, birthdays, patterns like "123" or "qwerty", and common substitutions (@ for a, 0 for o). Attackers know these patterns and exploit them. Randomly generated passwords have maximum entropy because every character position is truly unpredictable.
Including symbols (!@#$%^&*) increases the character set from 62 (letters + numbers) to 94, which significantly increases entropy. A 16-character password with symbols has 105 bits of entropy versus 95 bits without. However, some websites restrict which symbols are allowed, so you may need to adjust.
NIST (National Institute of Standards and Technology) no longer recommends routine password changes. Instead, change passwords only when there is evidence of compromise — such as a data breach notification, suspicious account activity, or if you shared the password. Frequent changes often lead to weaker passwords.
This password generator runs entirely in your browser — no passwords are sent to any server. The generation uses JavaScript Math.random() on your device. For maximum security, you can also use your operating system built-in password generator or a dedicated password manager like 1Password, Bitwarden, or Apple Keychain.
A passphrase is a sequence of random words (like "correct-horse-battery-staple") instead of random characters. Passphrases are easier to type and remember while still providing high entropy. A 4-word passphrase from a 7,776-word dictionary has about 51 bits of entropy. For equivalent security to a 16-character random password, use 5-6 random words.
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