Magnitudes of the volume-averaged magnetic field have been derived for a representative sample of 146 late-type galaxies using the minimum-energy condition and a simple model for the distribution of radio-emitting plasma within these galaxies. The distribution of derived magnetic fields is narrow (B eq = 0.29 ± 0.11 nT) and skewed to higher values. There is little or no dependence of the derived magnetic field on galactic type, although the archetypal starburst M82 is anomalous. We find no correlation between the scatter in the far-infrared/radio correlation and variation in the derived strength of the magnetic field