This test method is used by engine manufacturers, petroleum refiners and marketers, and in commerce as a primary specification measurement related to the matching of fuels and engines.

The cetane number is determined in a precombustion chamber type compression ignition test engine at a constant speed. This method can be used for conventional middle distillate Diesel fuel, jet kerosene fuels, blending feedstocks, as well as unconventional fuels like synthetics, vegetable oils, and bio-diesel.

This test method involves determining the quality of diesel fuel using a standard single cylinder four-stroke cycle variable compression ratio, indirect injection diesel engine. The quality is measured on an arbitrary scale of cetane numbers, ranging from 0 to 100. However, typical testing is usually conducted within the range of 30 to 65 cetane number.