How to Generate Strong Passwords and Passphrases That Are Actually Secure
File Tools Online · June 2026 · 8 min read
Most people understand they should use strong passwords. Fewer understand what strong actually means, and even fewer use a systematic approach to generating passwords that are both genuinely secure and practically usable. This guide covers the principles and practice of password generation.
What Makes a Password Strong?
Password strength is determined by entropy, the measure of randomness or unpredictability. A password with high entropy takes impractically long to crack even with sophisticated hardware. The factors that affect entropy are:
- Length, The single most important factor. Each additional character multiplies the number of possible passwords.
- Character set size, Using uppercase, lowercase, numbers, and symbols increases the options per character
- Randomness, A password must be genuinely random, not based on predictable patterns
| Password Type | Example | Entropy | Crack Time (2026 hardware) |
|---|---|---|---|
| Common word + number | Password123 | ~20 bits | Seconds |
| 8-char mixed | K#9mZ&2p | ~52 bits | Hours to days |
| 12-char mixed | K#9mZ&2pQr!v | ~78 bits | Years |
| 16-char mixed | K#9mZ&2pQr!vTu@8 | ~104 bits | Centuries |
| 4-word passphrase | correct-horse-battery-staple | ~44 bits | Thousands of years* |
| 6-word passphrase | marble-coffee-river-lamp-fox-north | ~77 bits | Effectively infinite* |
*Passphrase entropy assumes random word selection from a large dictionary, not predictable phrases
Password Types for Different Purposes
Complex Passwords, For Password Manager Storage
If you use a password manager (which you should), complex random passwords like K#9mZ&2pQr!vTu@8 are ideal. You never need to remember or type them, the password manager handles everything. Use 16+ character complex passwords for all accounts stored in a password manager.
Passphrases, For Memorisation
For the handful of passwords you must actually remember, your password manager master password, computer login, and a few critical accounts, passphrases are dramatically better. Four to six random common words are easier to remember than a string of random characters but provide equivalent or better security. "Marble coffee river lamp" is memorable and has enormous entropy if the words were chosen randomly.
PINs, For Device Access
For PINs limited to digits, length matters most. A 6-digit PIN has 1 million possibilities; an 8-digit PIN has 100 million. For high-security scenarios, use the maximum PIN length your device supports.
File Tools Online Password Generator
The Password Generator tool creates five types of passwords:
- Complex (random mix of uppercase, lowercase, numbers, symbols)
- Memorable (real words in uncommon combinations)
- PIN (digits only, specified length)
- Passphrase (random dictionary words, hyphen separated)
- Bulk (generate 50 passwords at once in a text file)
All passwords are generated server-side using cryptographically secure random number generation, not the weaker Math.random() that browser-based generators often use.