Infrared luminosities measured for 11 ALPINE FIR continuum-detected nonmerger galaxies (Béthermin et al. 2020) as a function of their CO(1–0) luminosities inferred from the [C II] molecular gas masses and a range of CO-to-H₂ conversion factors (dotted red lines) from the Milky Way value of 4.36 M_⊙ (K km s⁻¹ pc²)⁻¹ (on the left) to the starburst value of 1 M_⊙ (K km s⁻¹ pc²)⁻¹ (on the right). The solid black line shows the best fit of Dessauges-Zavadsky et al. (2015) of the empirical L_IR– relation with the 1σ dispersion of 0.38 dex (dashed black lines). Within this dispersion, the ALPINE [C II]-derived molecular gas masses lie on the relation for the Milky Way α_CO.