Foam fluids are widely used in petroleum industry such as foam-enhanced hydrocarbon recovery, underbalanced drilling, and as proppant carrying fluid in hydraulic fracturing. The most important issue to be considered in foam behavior is foam rheology and specifically, apparent viscosity. Various models have been used in order to predict foam apparent viscosity; most of these equations are originally developed for suspension systems, containing rigid spherical particles, and therefore, they are unable to predict foam apparent
viscosity with acceptable accuracy. In addition, the lack of a comprehensive model with usage in all foam qualities is still tangible in the literature. In this research, a new general empirical model with application in all foam qualities is proposed and validated against experimental data available in the literature. Despite the simplicity, results have near-unity correlation of determination (R2), which shows good agreement of the proposed model with experimental data. Additionally, a new definition for foam quality is presented, to be more representative of the foam texture.