Scoville Heat Units are used to specify of the hotness of food, specifically chili peppers. In 1912 Wilbur Scoville, devised a system to determine how hot foods are. He used a panel of tasters to provide heat scores for different peppers. Although we still use Wilbur's name for the Scoville Heat Units, the current method is much more scientific.

The sensation of heat that we experience from eating certain peppers is attributable to a chemical called capsaicin. The more capsaicin present in a pepper, the hotter it will seem. Although the Scoville scale spans from 0 to 16 million, the American Spice Traders Association (ASTA) set the standard for conversion from ppm (parts per million) of capsaicin to Scoville Heat Units as 1:15. This means that a sweet bell pepper has 0 Scoville units because there is no capsaicin present, and pure capsaicin crystals have 15,000,000 Scoville Heat Units (or 16 million, depending on who you ask.

As is evident from the table below, Scoville Heat Units vary widely from one species to the next. The hottest pepper ever grown is the Naga Jolokia from Assam, India which has a Scoville score of 855,000! There are also variations of heat from one pepper to the next within the same species; growing conditions, soil and other factors have an affect on the amount of capsaicin within a given pepper. The Scoville Heat Units listed below represent the average minimum amount detectable within the item in question, but keep in mind that the amount of capsaisin in any single type of pepper can vary greatly: