Biodiesel is produced in the United States to D 675 1, an ASTM standard. The source material in this fledgling industry in the U.S. is primarily soy oil, though other sources such as canola oil, waste oils, and greases from food and other sources are beginning to be exploited. At present, the referenced ASTM standard does not specify cloud and pour points values that are much higher for biodiesel than diesel derived from petroleum but allows them to be specified by the customer. There can be significant variation in these values, depending on the nature of the source material used to produce biodiesel, all of which meet the ASTM standards. This has the potential to create problems in applications as the quality of the biodiesel produced could vary widely. This study focused on quantitative measurements of cloud points of blends of biodiesel made from different sources. A correlation of these measurements with the saturated components was developed and was shown to correlate data reported in the literature as well.