Strong Password Generator
Make random passwords in your browser from letters, digits and symbols, and see exactly how many bits of randomness each setting gives.
A strong password generator picks every character at random, so the password has no pattern a guesser can exploit. This one draws from up to 94 characters using your browser's cryptographic random source and shows the exact strength of the choice. The default, 16 characters with at least one lowercase letter, uppercase letter, digit and symbol, carries 104.6 bits, labelled very strong. Twelve lowercase letters alone carry 56.4 bits, labelled fair.
Strength figures describe the random choice made by this page under the settings shown; the weak to very strong labels are ManyTools' own thresholds, not a standard. How a password is stored and used decides how safe it stays.
Your password
Press Generate.
- Strength of the random choice
- 104.6 bits, very strong
- Characters to choose from
- 94
Made in your browser. Nothing is sent to ManyTools or saved.
Embed this calculator on your site →
About the Strong Password Generator
Strength here is a count, not an opinion. The page works out how many different passwords your settings could produce, all equally likely, and takes the base-2 logarithm of that number: each extra bit doubles the guesses an attacker needs in the worst case. With all four character types on, there are 94 characters to choose from, so each added character adds about 6.55 bits; with lowercase letters alone each adds about 4.7. Asking for at least one of each type removes the passwords that miss a type and lowers the total a little, which the figure accounts for exactly rather than ignoring. Leaving out look-alikes such as 0 and O or 1, l and I shrinks the pool to 86 characters, costing about 2 bits at 16 characters, a fair trade when someone has to read the password aloud or type it from paper. The weak, fair, strong and very strong labels are ManyTools' own cut-offs at 40, 60 and 80 bits. Every password is made on your device; nothing is sent to ManyTools or stored, and refreshing the page clears it.
Frequently asked questions
How long should a password be?+
Sixteen random characters from all four types gives 104.6 bits, far beyond what guessing can reach, and is the default here. Eight characters with the same settings, one of each type, gives 51.3 bits, labelled fair. Length matters more than symbols: each extra character multiplies the possibilities by the size of the pool, while adding symbols only grows the pool from 62 to 94.
Is a password from this page safe to use?+
The randomness is: each character comes from your browser's cryptographic random generator, mapped onto the character pool with a method that throws away the rare values that would favour some characters. Safety after that depends on how you keep it. Use a different password for every account and store them in a password manager rather than reusing one or writing it into a document.
Why does the strength say bits instead of a time to crack?+
A crack time depends on how fast an attacker can test guesses, which ranges from a few per second against a login page to billions per second against a stolen password file. Bits stay the same whatever the attack: they count the possibilities. Each bit doubles them, so 80 bits is 2 to the 80th power, about 1.2 septillion, equally likely passwords.
Does the strength apply to a password I make up myself?+
No. The figure describes a password chosen at random by this page. A password a person invents, such as a word with a number on the end, has far fewer real possibilities than its length suggests, because people choose in predictable ways.
Embed this calculator
Free to use on your own site. Paste this snippet where you want the strong password generator to appear — it resizes itself automatically.
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