A crack is a shortened word for the value of a refined oil product against the underlying crude price. It is a reference to the refining cracking process to convert crude into a refined product. The better the crack price, the more a refiner will look to maximise the yield on that product. To calculate the crack, a given refined product price is converted from metric tonnes or gallons to a barrel equivalent price to provide an accurate reference against crude prices. Product cracks are used to assess the refinery margin, a crucial indicator for refiner demand. They are a useful gauge of product-specific health, as the correlation with outright crude prices is removed.