Micro Tools
Advertisement

Entropy Calculator

Measure password strength in bits of entropy. Type a password to see its character pool, entropy score and estimated crack time. Checked locally, never sent anywhere.

Your password

Type a password to analyze. It never leaves this page.

Entropy analysis

Type a password above to see its strength.

Advertisement

What entropy means

Entropy measures password strength in bits: each bit doubles the number of guesses an attacker needs. A 40-bit password falls in seconds to modern hardware, while 80+ bits resist brute force for longer than the universe has existed. The score comes from password length multiplied by the size of the character pool it draws from.

Length beats complexity

Adding one character helps more than swapping letters for symbols. A 16-character passphrase of plain words can outscore an 8-character tangle of symbols, and it is far easier to remember. The crack-time estimate assumes 10 billion guesses per second, roughly a serious cracking rig.

Related tools

Password generatorStrong random passwords with a strength meter. Meme generatorClassic top and bottom text on any image. Download as PNG. Color palettesHarmonious palettes, palette from image, and contrast checker.

Entropy Calculator FAQs

How many bits of entropy is enough?
Aim for at least 80 bits for important accounts, which typically means 14+ random characters or a 5-6 word passphrase. Anything under 60 bits is crackable with modest resources.
Does this work for passphrases too?
The math assumes random characters, so multi-word passphrases score higher than their real strength if the words are common. For passphrases, count about 11-13 bits per random dictionary word instead.
Is my password sent to a server?
No. Analysis runs entirely in your browser. Never type a real password into any website you do not fully trust, including this one.
Why is length more important than symbols?
Each extra character multiplies the search space by the pool size. Going from 8 to 12 characters with the same character set multiplies guesses by the pool size four times over.
What is the 10 billion guesses per second figure?
A rough benchmark for a well-funded cracking setup against fast hashes. Slow, salted hashes used by good sites make real attacks far slower, but entropy is still the right way to compare passwords.
Advertisement