We have determined the densities of Si in the liquid, ρl(T), and solid, ρs(T), states as a function of temperature, T, by employing an image digitizing technique and numerical calculation methods in combination with an electrostatic levitator. The obtained density data can be fitted with the following equations: ρl(T) = ρl(Tm)−1.71×10−4(T−Tm)−1.61×10−7(T−Tm)2(g/cm3); ρs(T) = ρs(Tm)−2.63×10−5(T−Tm)(g/cm3),where Tm is the melting point, 1687 K, and ρl(Tm) and ρs(Tm) are 2.580 and 2.311 (g/cm3), respectively. The error involved in the determination is estimated to be ±0.006 (g/cm3). The ρl(T) value smoothly varies through Tm and does not indicate a reported anomalous density variation. The ρl(Tm) value is 2% larger than the literature value and the coefficient of the linear temperature dependence is approximately half of a reported value. The ρs(Tm) value closely agrees with the literature value. © 1997 American Institute of Physics.