Title: polar surface area
Long Title: IUPAC Gold Book - polar surface area
DOI: 10.1351/goldbook.11490
Status: current

Definition
Surface area over all polar atoms (usually oxygen and nitrogen), including any attached hydrogen atoms, of a molecule.

Notes
1) Polar surface area is a commonly used metric (c.f. molecular descriptor) for the optimisation of cell permeability. Molecules with a PSA of greater than \(\pu{1.4 nm2}\) are usually poor at permeating cell membranes. For molecules to penetrate the blood-brain barrier, the polar surface area should normally be smaller than \(\pu{0.6 nm2}\), although values up to \(\pu{0.9 nm2}\) can be tolerated.
2) Sometimes sulfur atoms are included in the definition.
3) The value of PSA depends on the conformation of the molecule and also the algorithm and atomic radii used in the calculation.

Related Terms
- descriptor: https://goldbook.iupac.org//terms/view/11436
- topological polar surface area (TPSA): https://goldbook.iupac.org//terms/view/11526

Source
- PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 252 (https://doi.org/10.1515/pac-2012-1204)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/11490/html
- json: https://goldbook.iupac.org/terms/view/11490/json
- xml: https://goldbook.iupac.org/terms/view/11490/xml

Citation: Citation: 'polar surface area' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.11490
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Accessed: 2026-08-07T23:58:25+00:00