Coronal (L_X, top panel) and chromospheric (L_Hα, middle panel; L_Ca, bottom panel) emission luminosities as a function of magnetic flux, Φ_B. Symbol size and color are the same as in Fig. 5. Linear power laws are reasonable approximations for X-ray, Hα, and Ca luminosities describing both rapid and slow rotators. Relations are provided in Eqs. (4)–(6). Ca H&K emission shows a saturation at magnetic flux density ⟨B⟩≈800 G (see Fig. 8). This limit is applied to the magnetic flux values in the bottom panel (Ca H&K), but no limit is applied in the other two panels.