Biodiesel or fatty acid alkyl ester is a promising source of energy. It is a renewable and biodegradable diesel fuel with less harmful emissions. Biodiesel density data as a function of temperature is needed to model the combustion process. In this work, the density and specific gravity of pure palm oil-based methyl and ethyl esters biodiesel were measured at various temperatures. The data obtained was validated with Janarthanan empirical equation and the method proposed by Spencer and Danner using modified Rackett equation. The critical properties of a palm oil-based methyl and ethyl ester biodiesel were estimated using two widely used methods: Ambrose’s method, and Joback modification of Lydersen’s method. The results of these two methods were employed to represent the properties of the pure components, the mixing rules for the Lee-Kesler equation were employed to compute the critical properties of the mixture. The experimental and estimated density values using modified Rackett equation gave almost identical values with differences less than 0.03%. The Janarthanan empirical equation performs equally with differences within 0.4 %. Simple liner equations for density are also proposed in this work.