In this paper simple estimation methods are presented to predict sulfur weight percentage in petroleum fractions and crude oils. Input data needed to use this method are molecular weight, refractive index, and specific gravity (SG). In cases in which molecular weight and refractive index are not available they can be estimated from the boiling point and SG of the fraction using appropriate methods. For crude oils, the C7+ part of the crude mixture was split into several pseudocompounds using the two-parameter distribution model proposed by Riazi (Ind. Eng. Chem. Res. 1997, 36, 4299-4307), and then for each fraction sulfur content was determined. The sulfur content of crude was then determined from its carbon number distribution (or boiling point distribution) and the estimated sulfur content of each pseudocompound. For 132 different fuels and petroleum products with molecular weight ranging from 75 to 1500 and sulfur contents up to 6%, an average deviation of about 0.15% was obtained to estimate sulfur weight percentage from the proposed method. For seven crude oils with sulfur contents up to 2.4%, the proposed methods gave an average deviation of 0.31%.