Despite the ubiquity of hydrogen bonding in biological systems and medicinal chemistry, the relative strength of different hydrogen-bond donors and acceptors is much less appreciated than other key structural quantities like pK a , bond-dissociation energy, or torsional preferences. Most frequently, the Brønsted acidity or basicity of a given functional group is used as a proxy for its hydrogen-bonding strength. Although this relationship can be valid along a narrow structural series, in general there is "little to no relationship" 8 between a molecule's Brønsted acidity and its hydrogen-bond-donor or acceptor characteristics. The strength of different hydrogen-bond acceptors can be measured experimentally by measuring the association constant with a model hydrogen-bond donor in a given solvent. Taking the base-10 logarithm of this association constant gives pK BHX , the strength of the hydrogen-bond acceptor. While pK BHX values can be measured for any combination of hydrogen-bond donor, hydrogen-bond acceptor, and solvent, for "a mixture of historical and technical reasons" (Laurence et al. While hundreds of pK BHX values have been experimentally measured under these conditions over the past three decades, there is still a need to compute hydrogen-bond-acceptor strength for new organic compounds. Experimental pK BHX measurements produce a single measure of hydrogen-bond-acceptor strength for the entire molecule, while rational design of functional molecules typically requires atom-level quantification of hydrogen-bond basicity.