The polarity of a radical intermediate profoundly impacts its reactivity and selectivity. To quantify this influence and predict its effects, the electrophilicity/nucleophilicity of >500 radicals has been calculated. This database of open-shell species entails frequently encountered synthetic intermediates, including radicals centered at sp, sp, and sp hybridized carbon atoms or various heteroatoms (O, N, S, P, B, Si, X). Importantly, these determined polarities have been validated for electronically diverse sets of >50 C-centered radicals, as well as N- and O- centered radicals. High correlations are measured between polarity and reactivity, as well as within parallel sets of competition experiments (across different radical types and reaction classes). These multipronged analyses show a strong relationship between the computed electrophilicity, ω, of a radical and its relative reactivity ( vs Δω slopes up to 40; showing mere Δω of 0.1 eV affords up to 4-fold rate enhancement). We expect this will enable reactivity and selectivity prediction (by harnessing polarity-matched rate enhancement) and assist with troubleshooting in synthetic reaction development.