Experimentally determined viscosities of cottonseed, olive, hazelnut, corn, sunflower, canola and soybean oils were used in the development of an equation for simple and rapid viscosity estimation based on the fatty acid composition. The parameters A and B in the Andrade Equation were derived from the constants determined from each fatty acid using a computer program. The obtained equation was tested in the estimation of the viscosities of vegetable oils and their binary mixtures. Predicted and experimental viscosity values were then compared and average absolute deviations (AAD) calculated as 1.78% for vegetable oils and 3.48% for their mixtures. Due to the reasonable accuracy, this method could be applied to the common vegetable oils and their blends. This study also represents a model for their viscosity prediction of the oils having different fatty acid compositions.