CALCULATE WITH CONFIDENCE

Counting, Permutations & Combinations

Password Combinations Calculator

Count possible strings across character pools, length ranges, and required character classes.

Counting & Combinatorics

Count possible strings from character classes

Inclusion–exclusion for requirements
  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
Try an example

Possible strings

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Enter valid values to see the result.

Your entries are calculated in this browser and are not submitted to 365CALCS.COM.

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Understand the subject

What does a password-combination count mean?

This calculator counts strings permitted by entered pools and requirements. It is a search-space size, not a real-world security verdict.

Use it to understand the mathematical effect of length, character-pool size, and required classes.

The relationship

The counting rule

See the structure

Remove strings that miss a required class

Worked example

Check the rule with a small case

With 2 letters and 1 digit, two-character strings requiring a digit give 3² − 2² = 5.

Interpret with care

Choose the right counting model

A mathematical count does not account for attacker knowledge, reuse, rate limits, storage, or account protection.

Use the Permutation & Combination Generator when a small case needs to be inspected rather than only counted.

Quick guide

How to use this calculator

  1. Enter the minimum and maximum string lengths.
  2. Enter the available size of each character class.
  3. Mark any classes that must appear at least once, then read the exact count.

Calculation method

Apply the product rule and inclusion–exclusion

Without requirements, a pool of p characters gives p^L strings of length L. Inclusion–exclusion removes strings missing one or more required classes, and length-range counts are summed.

Worked example

Two-character strings with a digit

With two letters and one digit, there are nine total strings and four letter-only strings.

3²−2² = 5

Supported inputs

Precision and limits

Discrete domain

Inputs are whole counts. Negative, fractional, grouped, and scientific-notation inputs are rejected.

Exact integers

Results use arbitrary-precision integers and are never rounded. Inputs and output size are bounded to keep the page responsive.

Character pools

The entered classes must be disjoint; a character must not be counted in more than one pool.

Security

This is a mathematical search-space count, not an estimate of password strength, cracking time, or account security.