A method for estimating the output temperature of the output compressor of a two-stage turbocharger. The method includes: storing a composite relationship relating temperature ratio across a pair of compressors of the two-stage turbocharger as a function of mass flow through such pair of compressors and pressure drop across the pair of the compressors; calculating the pressure ratio equal to the pressure at an input to the first one of the pair of compressors to the pressure at the output of the second one of the pair compressor; using the composite relationship and an output of a mass flow at the input to the first one of the pair of compressors and the calculated pressure ratio to determine the temperature ratio across the pair of compressors; and calculating the estimated output temperature of the second one of the pair of compressors by multiplying the determined temperature ratio across the pair of compressors by a temperature at the input of the first one of the pair of compressors.