This paper explains how a product's usefulness may be defined and measured. Many aspects of consumer product assessments are conducted sub-consciously and this process is closely examined. A product's usefulness can be evaluated by measuring its advantages over alternative solutions based on specific criteria associated with fundamentals needs. When multiple criteria are involved, different weights are assigned to each. It should take into account the context in which the product is used. For the purpose of this paper, we use a formula to determine the relative usefulness of a variety of products in different contexts. We conclude that aspects of product's usefulness, connected with sub-conscious human decision making processes, can be a major factor in predicting acceptance and rejection rates.