A combined numerical-experimental method that enables accurate prediction of not only the elastic moduli and tensile failure strengths of syntactic foams, but also accounts for the experimentally observed scatter in these measurements is presented. In general, for the systems studied, an increase in microsphere content resulted in an increase in tensile modulus and a decrease in tensile strength. At low particle loading ratios, the variance in the measured experimental strength can be almost entirely attributed to the distribution of inter-particle distances between the microspheres, whilst at high particle loadings, geometric variance in the microstructure is shown to be only partially responsible for the observed scatter in strength data. Thus, for the first time, a direct link between the underlying microstructure and the experimentally observed scatter in fracture strength is drawn and substantiated with modelling.