Left panel: SFR–Hα relation. The IGIMF version in comparison with the empirical power laws proposed by Kennicutt (1998) and Lee et al. (2009). The red and green solid lines are IGIMF1/3 computed for solar metallicity [Fe/H] = 0 and the dashed lines represent the case of sub-solar metallicity, [Fe/H] = −2. Right panel: corrections to the Kennicutt SFR_K–Hα relation (Eq. (17)). The true (IGIMF) SFRs are divided by the Kennicutt value. The Hα flux of LeoP is shown by the vertical dotted line in both panels. For example, from the left panel it is evident that the IGIMF1,3 models yield values of the SFR that are consistent with the presence of massive stars in the Leo P galaxy. The two panels show that dwarf galaxies with Hα fluxes near 10³⁶ erg s⁻¹ have a SFR that is more than 100 times larger than that suggested by the Kennicutt relation (Eq. (15)), while massive or profusely star-forming galaxies with Hα ≈ 10⁴⁴ erg s⁻¹ have SFRs that can be 10–100 times smaller than given by the traditional Kennicutt relation. As for the left panel the solid lines indicate solar metallicity [Fe/H] = 0 and the dashed lines indicate [Fe/H] = −2.