  We present a new determination of the local volume-averaged star formation
rate from the 1.4 GHz luminosity function of star forming galaxies. Our sample,
taken from the B<=12 Revised Shapley-Ames catalogue (231 normal spiral galaxies
over effective area 7.1 sr) has ~100% complete radio detections and is
insensitive to dust obscuration and cirrus contamination. After removal of
known active galaxies, the best-fit Schechter function has a faint-end slope of
-1.27+/-0.07 in agreement with the local Halpha luminosity function,
characteristic luminosity L*=(2.6+/-0.7)*10^{22} W/Hz and density phi* = (4.8
+/-1.1)*10^{-4} / Mpc^3. The inferred local radio luminosity density of
(1.73+/-0.37+/-0.03)*10^{19} W/Hz/Mpc^3 (Poisson noise, large scale structure
fluctuations) implies a volume averaged star formation rate ~2 x larger than
the Gallego et al. Halpha estimate, i.e. rho(1.4 GHz} = (2.10+/-0.45+/-0.04)
*10^{-2}$ Msun/yr/Mpc^3 for a Salpeter initial mass function from 0.1-125 Msun
and Hubble constant of 50 km/s/Mpc. We demonstrate that the Balmer decrement is
a highly unreliable extinction estimator, and argue that optical-UV SFRs are
easily underestimated, particularly at high redshift.
