The modelling approach employed here previously yielded accurate predictions for SnS and SnSe. While the Ge chalcogenides are not as well characterised, the present calculations appear to show similarly good agreement with available experimental measurements. The measurements on Pnma Ge 0.79 Ag 0.01 Sn 0.2 Se in Ref. obtained S ≈ 300 µV K -1 at 300 K with n ≈ 5 × 10 18 cm -3 , and we predict the same 300 K Seebeck coefficient with a 2× larger n = 10 19 cm -3 . The measurements on R3m (GeSe) 0.9 (AgBiTe 2 ) 0.1 in Ref. reported S ≈ 151 and 250 µV K -1 at room temperature and 723 K and a PF of 1.28 mW m -1 K -2 at 627 K, with a carrier concentration of 1.1 × 10 19 cm -3 . With a comparable n = 10 19 cm -3 we predict a power factor of 1.47 mW m -1 K -2 at 620 K and a S = 287 and 218 µV K -1 at 300 and 720 K, which we again consider to be reasonable agreement given that the experimental sample is an alloy. (We note that our calculations predict a very similar S = 156 and 251 µV K -1 at the two temperatures with increased carrier concentrations of 8 × 10 19 cm -3 and 10 20 cm -3 , respectively.)