The formula
How it works
Generate a strong, random password. Choose the length and which character types to include, then press Generate for a fresh password each time. It runs entirely in your browser.
FAQ
What makes a password strong?
Length and variety. A longer password with a mix of uppercase, lowercase, numbers and symbols has vastly more possible combinations, making it far harder to guess or crack. The calculator shows the entropy in bits — above about 60 bits is considered strong, and more is better for important accounts.
Is it safe to generate a password here?
Yes — the password is created in your browser and never sent anywhere. That said, for your most sensitive accounts a dedicated password manager, which both generates and securely stores passwords, is the best practice. Use a unique password for every account.
What exactly is entropy in bits?
Entropy measures how many equally likely passwords could have been generated with the same length and character pool, expressed as a power of two. Each extra bit doubles the number of possible passwords, so entropy is a compact way to compare password strength.
How long would it take to crack this password?
Crack-time estimates depend heavily on assumptions — the attacker’s hardware, whether the hash is slow or fast, and whether they guess randomly or use smarter strategies — so treat any single figure as a rough order of magnitude, not a guarantee. Higher entropy always pushes that estimate further out.
Does adding symbols help more than adding length?
Generally, length helps more. Each additional character multiplies the total combinations by the pool size, while adding a character type only enlarges the pool for every position, so a longer password with fewer character types often beats a short one with all four.
Should I avoid dictionary words and patterns?
Yes. Entropy calculations assume every character is chosen at random, but real attackers try common words, names and patterns first, so a password built from them is far weaker than its length alone suggests. A randomly generated password like this one avoids that weakness.
What length should I choose?
12 characters is a reasonable minimum today, and 16 or more is comfortable for important accounts, especially when combined with a password manager so you never need to remember it yourself.
About the password generator
This tool creates strong, random passwords to your specification. You choose how long the password should be and which character types to include — uppercase letters, lowercase letters, numbers and symbols — and it assembles a random string from those characters. It also estimates the password’s strength in bits of entropy, so you can see how hard it would be to crack.
How to use it
Set the length and switch on the character types you want, then press Generate. Press again for a different password. A longer password drawing on all four character types is the strongest; for example, a 16-character password with mixed case, numbers and symbols has well over 90 bits of entropy, far beyond what is practical to brute-force.
The formula
Password strength is measured as entropy, , where the pool size is the number of possible characters at each position. Adding character types enlarges the pool, and each extra character multiplies the total combinations, so entropy grows quickly with length. Higher entropy means exponentially more guesses are needed to break the password.
Where it is used
People use it whenever they need a fresh, unpredictable password — for a new account, a Wi-Fi network, or when replacing a weak or reused one. Because reusing passwords is a major security risk, generating a unique random one for each service is a simple, strong defence. Pair it with a password manager to keep track of them all.