Password Strength Meter

Password Strength Meter is evaluated from Password Length, Contains Lowercase? and Contains Uppercase?. The calculation reports Character Set Size, Possible Combinations and Entropy.

Results

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About the Password Strength Meter

Password Strength Meter is treated here as a quantitative relation between Password Length, Contains Lowercase?, Contains Uppercase? and Contains Numbers? and Character Set Size, Possible Combinations, Entropy and Time to Crack.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
Character set size is the total pool of possible characters. Entropy in bits = length x log₂(charset). Crack time assumes an attacker tries half the combinations on average before finding the right one.

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

Character set size is the total pool of possible characters. Entropy in bits = length x log₂(charset). Crack time assumes an attacker tries half the combinations on average before finding the right one.

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: Common 8-char password: lowercase + numbers only

Inputs

password_length: 8 has_lowercase: 1 has_uppercase: 0 has_numbers: 1 has_symbols: 0 guesses_per_second: 1000000000
Character Set Size: 36 chars. Possible Combinations: 2,821,109,907,456. Entropy: 41.4 bits. Time to Crack: 1,410.55 sec. Strength Score: 60 /100. Password Strength: Strong

With Password Length = 8, Contains Lowercase? = 1, Contains Uppercase? = 0 and Contains Numbers? = 1 as the stated inputs, the result is Character Set Size = 36 chars, Possible Combinations = 2,821,109,907,456 and Entropy = 41.4 bits. Each value corresponds to the declared output fields.

Example 2: Strong 12-char password: all 4 character types

Inputs

password_length: 12 has_lowercase: 1 has_uppercase: 1 has_numbers: 1 has_symbols: 1 guesses_per_second: 1000000000
Character Set Size: 94 chars. Possible Combinations: 475,920,314,814,253,359,955,968. Entropy: 78.7 bits. Time to Crack: 237,960,157,407,126.69 sec. Strength Score: 90 /100. Password Strength: Very Strong

With Password Length = 12, Contains Lowercase? = 1, Contains Uppercase? = 1 and Contains Numbers? = 1 as the stated inputs, the result is Character Set Size = 94 chars, Possible Combinations = 475,920,314,814,253,359,955,968 and Entropy = 78.7 bits. Each value corresponds to the declared output fields.

Example 3: Passphrases: 5-word passphrase (25 chars, lowercase only)

Inputs

password_length: 25 has_lowercase: 1 has_uppercase: 0 has_numbers: 0 has_symbols: 0 guesses_per_second: 1000000000
Character Set Size: 26 chars. Possible Combinations: 236,773,830,007,967,605,947,763,074,374,041,600. Entropy: 117.5 bits. Time to Crack: 118,386,915,003,983,800,444,125,184 sec. Strength Score: 60 /100. Password Strength: Strong

With Password Length = 25, Contains Lowercase? = 1, Contains Uppercase? = 0 and Contains Numbers? = 0 as the stated inputs, the result is Character Set Size = 26 chars, Possible Combinations = 236,773,830,007,967,605,947,763,074,374,041,600 and Entropy = 117.5 bits. Each value corresponds to the declared output fields.

Example 4: Maximum security: 20-char password, all character types

Inputs

password_length: 20 has_lowercase: 1 has_uppercase: 1 has_numbers: 1 has_symbols: 1 guesses_per_second: 1000000000
Character Set Size: 94 chars. Possible Combinations: 2,901,062,411,314,618,312,178,035,371,024,110,845,952. Entropy: 131.1 bits. Time to Crack: 1,450,531,205,657,309,213,031,378,452,480 sec. Strength Score: 90 /100. Password Strength: Very Strong

With Password Length = 20, Contains Lowercase? = 1, Contains Uppercase? = 1 and Contains Numbers? = 1 as the stated inputs, the result is Character Set Size = 94 chars, Possible Combinations = 2,901,062,411,314,618,312,178,035,371,024,110,845,952 and Entropy = 131.1 bits. Each value corresponds to the declared output fields.

Common Use Cases

  • Check if a password is strong enough
  • Estimate how long it would take to crack a password
  • Understand what makes passwords secure