Experimentally determined ∆G o acid, gas (AH) values are often measured relative to each other by means of measuring equilibrium constants between two neutral compounds and their anionic forms. These relative affinities are then anchored to the value for a reference compound. The uncertainty of relative ∆G o acid, gas (AH) measurements from these equilibrium measurements is cited as approximately 0.2 kcal mol -1 . However, anchoring the energy scale incurs a larger uncertainty, typically cited as around 2 kcal mol -1 . For this reason, a systematic offset caused by a difference in anchor values may exist between computed values and curated experimental data. An uncertainty of around 2 kcal mol -1 is typically cited for ∆G o acid, gas (AH), though most of the uncertainty is simply from the anchoring process.