The overrun is the difference between the amount of pure milk fat and the amount of butter manufactured from that given amount of fat.The difference between the amount of fat and the amount of butter is divided by the amount of fat and multiplied by 100.
Example: 700 pounds milk testing 6 per cent= 42 pounds fat. Yield of butter made from 42 pounds fat, is 50 pounds; difference is 8 pounds (overrun) percentage overrun is X 100=19%.
