The H-1 NMR chemical shifts were theoretically computed for the organic dyes 2-(2,6-dimethyl-4H-pyran-4-ylidene)-malononitrile (1), cyano-(2,6-dimethyl-4H-pyran-4-ylidene)-acetic acid methyl ester (2), 2-(2,6-bis(4- (dimethylamino)styryl)-4H-pyran-4-ylidene)-malononitrile (3), and methyl 2-(2,6-bis(4-(dimethylamino)styryl)-4H-pyran-4-ylidene)-2-cyanoacetate (4) at the GlAO/B3LYP/6-311++G(d, p)//B3LYP/6-311++G(d,p) level of theory. Moreover, the intramolecular rotational barriers of the molecules were calcu lated to evaluate the internal flexibility with respect to the torsional degrees of freedom, and the nuclear-independent chemical shifts (NICS) were employed to analyze the ring currents. The difference was explained in terms of intramolecular hydrogen bonds and ring currents of the molecules. The H-1 NMR spectra were reproduced by experiments for the comparison with computationally constructed data. Our results suggest a good guideline in interpreting H-1 NMR chemical shifts using computational methods and furthermore a reliable perspective for designing molecular structures.