Although hazardous waste lists and their classification methodologies are nearly the same in most of the countries, there are some gaps and subjectiveness in determining the waste as hazardous waste. A rating system for the determination of waste as a hazardous waste is presented in this study which aims to overcome the problems resulted from the existing methodologies. Overall rating value (ORV) calculates and quantifies the waste as regular, non-regular or hazardous waste in an "hourglass" scale. "ORV" as a cumulative-linear formulation in proposed model consists of components such as ecological effects of the waste (Ee) in terms of four main hazard criteria: ignitability, reactivity, corrosivity and toxicity; combined potential risk (CPR) including carcinogenic effect, toxic, infectious and persistence characteristics; existing lists and their methodology (L) and decision factor (D) to separate regular and non-regular waste. Physical form (f) and quantity (Q) of the waste are considered as factors of these components. Seventeen waste samples from different sources are evaluated to demonstrate the simulation of the proposed model by using "hourglass" scale. The major benefit of the presented rating system is to case the works of decision makers in managing the wastes. (c) 2005 Elsevier B.V. All rights reserved.