Most studies about online consumer behavior have not considered the weight of each item corresponding to its particular decision-making style. As a result, there are not any measures of online consumers' scores for each decision-making style. Research has found that online consumers have different decision-making styles when purchasing product items. Therefore, measuring online consumers' decision-making styles is vital as it can be used to find out suitable product items for these consumers. This paper measures the score of each decision-making style based on the factor score coefficients. Finally, the factor score coefficient ontology is developed and expanded into an online consumers' decision-making style ontology so that it can be utilized by different emarketing applications that exploit online consumer behavior.