The free energy of formation of molecular-size cavities, DeltaG(cav), in 12 organic liquids of common use as solvents is obtained from free energy perturbation simulations. They are acetone, cyclohexane, ethanol, toluene, chlorobenzene, benzene, tetrachloromethane, dichloromethane, chloroform, mesitylene, o-xylene, and tetrahydrofuran. The results are (1) cast in a simple way that should lead to an improvement over the most commonly used Pierotti equation for the calculation of DeltaG(cav) in quantum chemical computer programs and (2) used for assessing the relative contribution of cavitation free energy to the total solvation free energy in a set of nearly 100 solvent/solute pairs.