Recent improvements to thermodynamic perturbation theory equations of state are reformulated to yield a simplified equation of state for hard-sphere chains (STPT-D). The properties of the hard chain can be obtained solely from the hard-sphere compressibility, the hard-sphere site-site correlation function, and an empirical parameter calculated from molecular simulation data for the second virial coefficient of hard-sphere chains. The STPT-D equation is applied to the prediction of both the compressibility of 4-, 8-, 16-, 51-, and 201-mer hard-chains and the second virial coefficients of up to 128-mer chains. Comparison with molecular simulation data indicates that the STPT-D equation generally predicts both the compressibility and the second virial coefficient more accurately than other equations of state.