Variant Configuration Combination Calculator: How Many Configurations Can Your Product Have?
Every added option multiplies the number of possible configurations. This calculator shows the raw count, the valid count after your rules, and why testing every one is not realistic, with a lower bound for pairwise coverage.
Your numbers
For example colours or finishes.
For example voltage options.
Use 1 for any characteristic you do not need.
After constraints and preconditions remove impossible combinations.
Your results
Figures are planning estimates. The pairwise lower bound assumes six characteristics and is a minimum, not a generated test set. Real covering arrays need a tool and the rules of your model.
Valid configurations as characteristic 1 grows
Sweeps Characteristic 1 values from 2 to 30, holding your other inputs fixed.
Need a test strategy for a large option set?
Optional expert review of your configuration test matrix and regression approach.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter the number of allowed values for up to six characteristics, using 1 for any you do not need. Set the share of valid combinations, which you can estimate from your rule catalogue or measure by counting in a variant table. Enter the minutes a tester needs per configuration. The tool returns the raw total, valid configurations, the full test time, and a minimum pairwise test count. The chart sweeps the first characteristic to show how quickly the count grows when one list gets longer.
The maths behind it
The raw total is the product of the value counts. With 8, 5, 6, 4, 3 and 10 values that is 28,800 combinations, and 35 percent valid is roughly 10,080. Pairwise testing aims to cover every pair of values from two different characteristics at least once. The number of such pairs is the sum over all characteristic pairs of the product of their sizes, which equals half of the square of the total values minus the sum of squares. Each test of six characteristics covers 15 pairs, so the pairs divided by 15 is the minimum number of tests.
- Raw total = product of value counts
- Valid = raw total times valid share
- Pairs = ((sum)^2 - sum of squares) / 2
- Minimum pairwise tests = pairs / 15, rounded up
How to use the results
If the full test time runs into hundreds of hours, plan a test matrix: one case per option, one per rule, and a set of pairwise cases for interactions. If the invalid count is huge, rely on constraints and variant tables rather than long nested preconditions, and test that blocked combinations give a clear message. Revisit the numbers when you add an option, because one new value in a large characteristic can add thousands of combinations. Use the result in your test plan and as a scope argument when stakeholders ask for more options.
Frequently Asked Questions
Why is the raw number so much larger than the valid number?
Because most options have rules: certain voltages need certain motors, certain finishes are only for certain sizes. Those rules remove impossible combinations. The better your constraints, the larger the gap, and the more important it is to test that the blocked ones really are blocked.
What is pairwise testing?
Pairwise or all-pairs testing is a technique that selects a small set of tests so that every pair of values from two different characteristics appears together at least once. It finds many interaction faults with far fewer tests than exhaustive testing.
Is the pairwise number exact?
No, it is a lower bound. A real covering array is usually larger and depends on your rules, since some pairs are invalid and cannot be tested. Use a pairwise generator tool and your valid-combination rules to produce the actual set.
How do I find my valid share?
Count valid combinations from a variant table or a model export if you have one, or estimate from the rule catalogue by applying exclusions one at a time. Even a rough range of say 20 to 50 percent is enough for planning.
If you want help designing a test matrix or a regression process for a configurable product, Netray can arrange an expert review.
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