The C-Score is a combination of your domain scores. It is calculated from the product of reasoning, short-term memory, and verbal ability, which are calculated from your test scores (learn more).
Notice that it is based on a product of scores, rather than a sum or an average. You can think of your C-Score as a three-dimensional box, with each domain score as one measurement (width, height, and depth). The bigger the volume of the box, the higher your C-Score. The higher your C-Score, the higher your mental capacity is today.
Your C-Score is designed so that it has the most meaning when you track it from day to day and see how your scores vary in response to your lifestyle. So, changes matter more than the absolute number. However, to give you an idea of what the number means: it is designed so that a C-Score of 12.5 is about average.
Why Isn't the C-Score Just an Average of My Test Scores?
The C-Score is similar to an average, in that it combines several scores. However, it has advantages over a simple calculation of an average:
It is not affected as much by extreme scores. For example, if you're having a very good day, but only on one test, your C-Score will not skyrocket. However, if your overall mental performance is high and you raise your score in all domains, your C-Score will soar.
The C-Score rewards being well-rounded in all the domains, in other words.
Improvements to your lowest domain score will have a bigger effect than improvements to what you are already good at. Check the FAQs on each domain to discover which tests affect which domains.
Think of it like a box again. If your box is squished like a pancake because the height dimension is low, and you want a box that holds more, you are better off raising the height than making the base a bit bigger than it already is.
If it were just an average, improvement in any domain would have an equal effect on your C-Score. Instead, improvements in the lowest domain have the biggest effect.
We believe this better reflects what you think of as the overall capacity of your brain. It also motivates improvement in your weakest areas, rather than only showing off your strengths. Want a better C-Score? Work on your weakest areas.
For these reasons, we believe the C-Score is an accurate and practically useful summary of the cognitive abilities that our tests measure.