© 2014 Elsevier Inc.All rights reserved. We describe a robust screening technique that correlates the surface area of metal-organic frameworks to the proton T2relaxation behavior of imbibed solvent at low field (13 MHz). In frameworks with small pore sizes (1 nm) lead to corresponding increases in the rate of solvent exchange, as confirmed by T2relaxation exchange (REXSY) experiments; increases in the pore size also increases the T2of the pore-confined solvent. The combination of these two effects results in comparable rates of relaxation and exchange, which precludes the direct analysis of Laplace inversions. Thus, two- and three-site kinetics models were applied to extract porosity from relaxation decays, thereby improving the utility of the porosity screening tool.