The heat level of red peppers can vary depending on the type of pepper, as well as other factors such as the growing conditions and the way they are prepared. In general, however, the smaller and more slender the red pepper, the hotter it tends to be.
One of the hottest types of red pepper is the Carolina Reaper, which has been recognized by Guinness World Records as the world's hottest pepper. It has an average heat level of over 1.5 million Scoville heat units (SHU), which is significantly hotter than other popular peppers like habaneros (100,000-350,000 SHU) or jalapenos (2,500-8,000 SHU).
Other types of red peppers that are known for their heat include Thai Bird's Eye chili peppers, Cayenne peppers, and Scotch Bonnet peppers. However, it's important to note that heat levels can vary even within the same type of pepper, and some individuals may find that their tolerance for spicy foods is different than others.