alpha- and beta-D-glucopyranose monoacetates 1-3 were prepared with selective C-13 enrichment in the O-acetyl side-chain, and ensembles of C-13-H-1 and C-13-C-13 NMR spin-couplings (J-couplings) were measured involving the labeled carbons. Density functional theory (DFT) was applied to a set of model structures to determine which J-couplings are sensitive to rotation of the ester bond theta. Eight I-couplings ((1)J(CC) (2)J(CH), (2)J(CC) (3)J(CH), and (3)J(CC)) were found to be sensitive to 0, and four equations were parametrized to allow quantitative interpretations of experimental J-values. Inspection of I-coupling ensembles in 1-3 showed that O-acetyl side-chain conformation depends on molecular context, with flanking groups playing a dominant role in determining the properties of theta in solution. To quantify these effects, ensembles of I-couplings containing four values were used to determine the precision and accuracy of several 2-parameter statistical models of rotamer distributions across theta in 1-3. The statistical method used to generate these models has been encoded in a newly developed program, MA'AT, which is available for public use. These models were compared to O-acetyl side-chain behavior observed in a representative sample of crystal structures, and in molecular dynamics (MD) simulations of O-acetylated model structures. While the functional form of the model had little effect on the precision of the calculated mean of theta in 1-3, platykurtic models were found to give more precise estimates of the width of the distribution about the mean (expressed as circular standard deviations). Validation of these 2-parameter models to interpret ensembles of redundant I-couplings using the O-acetyl system as a test case enables future extension of the approach to other flexible elements in saccharides, such as glycosidic linkage conformation.