Capsaicin is what gives peppers their heat and is measured by a scale called the Scoville Heat Unit (SHU). To give you an idea of the scale a sweet pepper has 0 SHU, whereas one of the hottest peppers, the Ghost pepper, has 1,000,000 SHU! A moderate heat hot pepper would have a range of 6,000 to about 25,000 SHU.