A scaling analysis of burner-supported spherical-diffusion-flame extinction brought about by radiative heat loss is presented. The results are compared against earlier microgravity experimental data and unsteady numerical computations with detailed chemistry available in the literature, for normal and inverse flames. The flame diameter at extinction is shown to correlate well with the present model, in which the extinction radius scales with one-third power of gas flow rate times reactant mass fraction divided by the Planck-mean absorption coefficient. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.