Dust emission at rest-frame 850 μm per unit mass of gas, L_ν(850 μm) /M_gas, plotted for our low-L_IR-selected SFGs (squares) and our comparison sample of z> 1 SFGs with CO measurements from the literature and published far-IR/submm photometry (triangles). Only SFGs with metallicities Z/Z_⊙> 0.8 are considered. These results are compared with the compilation from Scoville et al. (2014) for the SMGs at z = 1.4−3 and local spirals and ULIRGs. We assume a “Galactic” CO−H₂ conversion factor for all objects and M_gas ≃ M_H2 for high-redshift galaxies. All galaxies have a similar L_ν(850 μm) /M_gas within 1−2σ, with a trend toward a lower dust-to-gas ratio in z> 1 SFGs by ~ 0.33 dex at fixed near-solar metallicity, as shown with the lines corresponding to the L_ν(850 μm) /M_gas means of local spirals and ULIRGs (blue dotted line), high-redshift SMGs (green dashed line), and z> 1 SFGs (red solid line), respectively.