Used cooking oil specifications vary by end use, but generally, a good quality used cooking oil for biodiesel production or other applications will have a free fatty acid (FFA) content of 3% or less. This ensures that the oil can be converted into biodiesel without requiring additional processing steps.

Also crucial for quality used cooking oil is a moisture and impurities (MIU) level of 0.1% or less, and a specific gravity around 0.915, which refers to the density of the oil. Other key characteristics include a saponification value (around 186 mg KOH/g), iodine value (around 120), and a flash point of at least 220°C.

The saponification value measures how easily the oil can react with a base to form soap, and the iodine value indicates how easily the oil can be hydrogenated. Used cooking oil that meets these specifications is considered good quality oil and can be used for a variety of applications including biodiesel production and chemical synthesis.