Thermodynamic property relations for liquid 3He-4He mixtures at saturated pressure based on experimental measurements of the specific heat are determined. The relations are valid over the entire concentration range and for temperatures from 0.15 K to 1.8 K. Thermodynamic properties are first determined in the two-phase region, and then extended to the single-phase He-II and He-I regions. The results are in good agreement with some other 3He-4He mixture property data, though the scarcity of experimental data in large parts of the region of interest precludes a more thorough comparison. We derive some thermodynamic quantities that may be useful to the analysis of heat exchangers and throttles with superfluid 3He-4He flows. We also discuss how these properties can be extended to higher pressures.