The principles of demand and exclusion can be used to estimate the number of people who would be unable to use the kettle shown opposite. For the sake of simplicity, the results only consider vision and dexterity.

The tasks required to use the kettle are identified as: separate kettle from power source, carry to water source, fill the kettle to desired level, re-attach to power source, switch on, and finally, pour the boiling water into mug. The level of design exclusion for an ideal kettle would be no greater than the number of people who would be unable to pick up and drink hot liquid from a mug, which is also analysed for comparison.

The revised capability scales were used to assess the demand level for the tasks required to use each product, then the exclusion calculator was used to estimate the proportion of the population that would be unable to perform these tasks.

The combined number of people excluded from using the kettle (7.0%) is less than the total for each separate capability (6.5 + 0.9 = 7.4%), because some people have both low dexterity and vision capability, but are counted only once in the combined exclusion estimate.