A lot of people are asking what the Scoville units are on our hot sauces lately, likely due to the popularity on the YouTube series Hot Ones. In this show, the scoville units of each bottle is shown as a gauge. What most folks don't realize is that it's the show that tests them, not the manufacturers, and that the test only applies to that specific bottle/batch of that sauce.
In order for a manufacturer to state on the label that the sauce is a SHU, they would need to test each individual batch of that sauce and revise the label each time due to variations in the natural spicy ingredients themselves. So while it's a great gauge for the show, and is accurate in that application, it's not a practical heat guide for a company producing several batches per day.
For this reason we've always used our slightly tongue in cheek Burn Rate from 1-10, that sometimes goes to 12 or right off the charts. If you like cayenne sauces, and ours are a 4-5 on the heat scale, you get a rough idea of what you're getting in to when you buy a 9. The gamble is half the fun! The Scoville scale is a measurement of the pungency (spiciness or "heat") of chili peppers and other spicy foods, as recorded in Scoville Heat Units (SHU) based on the concentration of capsaicinoids, among which capsaicin is the predominant component. The scale is named after its creator, American pharmacist Wilbur Scoville, whose 1912 method is known as the Scoville organoleptic test. In the 21st century, high-performance liquid chromatography (HPLC) is used to quantify the capsaicinoid content as an indicator of pungency. - Wikipedia