Passphrase Strength Meter
Check a multi-word passphrase: word count, EFF wordlist matches, diceware entropy if chosen randomly, and a realistic zxcvbn score. Runs locally.
Type a password above to analyze it. Nothing is sent anywhere.
Runs entirely in your browser. Your data is never uploaded.
What is Passphrase Strength Meter?
This meter is made for passphrases of several words. It counts the words, checks which ones are in the EFF diceware wordlist, calculates the entropy they would have if chosen randomly, and shows the zxcvbn score that accounts for quotes, common phrases and dictionary words.
How to use Passphrase Strength Meter
- Type the passphrase into the Passphrase field.
- Check the number of Words and Words in EFF list.
- If all words are in the EFF list, read the entropy If chosen randomly (EFF).
- Compare with the zxcvbn score and follow the suggestions.
Example
cactus dolphin glacier tulip
Words 4, in EFF list 4/4, 51.7 bits if chosen randomly; zxcvbn score 4/4 (Very strong)
When to use Passphrase Strength Meter
Use it to judge a passphrase for a master password, disk encryption or Wi-Fi. If you picked the words yourself, trust the zxcvbn result more than the diceware bound.
How Passphrase Strength Meter works
Words are split on spaces, punctuation and other non-letter characters. If every word is in the 7,776-word EFF list, the diceware bound is words × log2(7776) ≈ 12.9 bits per word, which is correct only if the words were rolled with dice or a secure RNG. zxcvbn-ts independently scores the phrase against common passwords, English words, names and Wikipedia text, catching quotes and well-known phrases.
Common Use Cases
- Checking a password-manager master passphrase
- Comparing 4-word and 6-word passphrases
- Spotting passphrases built from famous quotes
- Verifying diceware passphrases after rolling dice
FAQs
Why does the EFF entropy assume random selection?
People choose related or familiar words, which attackers model. Only words selected by dice or a secure RNG reach 12.9 bits each.
Do capital letters or digits help a passphrase?
A little, but adding another random word adds about 12.9 bits, more than most decorations.
Is a song lyric a good passphrase?
No. Lyrics, quotes and proverbs are in cracking dictionaries even though they are long.