Differential path length spectroscopy (DPS) is a method of reflectance spectroscopy that utilizes a specialized fiber geometry to make the photon path length insensitive to variations in tissue optical properties over a wide range of absorption and total scattering coefficients, which are common within the ultraviolet/visible (UV/VIS) wavelength region. This study extends the description of to larger and smaller values, optical properties that are representative of the near-infrared region (NIR), a region where the DPS path length may be dependent on both coefficients. This study presents a novel empirical relationship between and the combined effect of both (range: ) and (range: ), anisotropy of 0.8, and is applicable to DPS probes containing a wide range of fiber diameters (range: ). The results indicate that the simple empirical formula, including only one fitted parameter, is capable of accurately predicting over a wide range (; range: ) and predictions are not biased versus or . This novel relationship is applicable to analysis of DPS measurements of tissue in both the UV/VIS and NIR wavelength regions and may provide information about the wavelength-specific tissue volume optically sampled during measurement.