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Calcimator

Password Entropy Calculator

Calculate password entropy, brute force time, and security strength. Measure password complexity and cryptographic strength.

Inputs

characters

Results

Password Entropy

78.7 bits

Brute Force Time

7,540,500 years

Equivalent Key Length

78.7 bits

Possible Passwords475,920,000,000,000,000,000,000
How to Use This Calculator
  1. Set the password length in characters.
  2. Select the character types used: uppercase, lowercase, numbers, and/or symbols.
  3. Review password entropy in bits -- aim for 72+ bits for most accounts, 120+ for high-security.
  4. Check the equivalent brute-force time in years at modern cracking speeds.
  5. Use these benchmarks to set minimum password requirements in your security policy.

How the result changes with Password Length

Password LengthPassword EntropyBrute Force TimeEquivalent Key Length
1491.8 bits66,627,900,000 years91.8 bits
45295 bits978,632,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years295 bits
84550.6 bits87,620,500,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years550.6 bits
115753.8 bits1,286,970,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years753.8 bits

What each input means

Password Length
Length of password
Character Set Size
Number of possible characters (if not using checkboxes)
Uppercase Letters
Include A-Z
Lowercase Letters
Include a-z
Numbers
Include 0-9
Symbols
Include special characters

How this is calculated

Formula

Entropy = Length × log₂(Character Set Size)

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Password Length = 12, Character Set Size = 94, Uppercase Letters = 1, Lowercase Letters = 1 = 6 input(s) provided
  2. Calculate Password Entropy
    Password Entropy
    78.7 = 78.7
  3. Calculate Brute Force Time
    Brute Force Time
    7540500 = 7540500
  4. Calculate Equivalent Key Length
    Equivalent Key Length
    78.7 = 78.7
  5. Calculate Possible Passwords
    Possible Passwords
    4.7592e+23 = 4.7592e+23

Engine last updated . Checked against 6 independently-derived tests — how we verify calculators.

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