PIXEL has been used to perform calculations of adsorbate-adsorbent interaction energies between a range of metal-organic frameworks (MOFs) and simple guest molecules. Interactions have been calculated for adsorption between MOF-5 and Ar, H2, and N2; Zn2(BDC)2(TED) (BDC = 1,4-benzenedicarboxylic acid, TED = triethylenediamine) and H2; and HKUST-1 and CO2. The locations of the adsorption sites and the calculated energies, which show differences in the Coulombic or dispersion characteristic of the interaction, compare favourably to experimental data and literature energy values calculated using density functional theory.