What is the Scoville Scale?

The Scoville scale is a measurement of pungency (or spiciness) of chili peppers, measured in Scoville Heat Units (SHUs). The Scoville scale is named after Wilbur Scoville, the pharmacist who created the scale in 1912.

A Brief History of the Scoville Scale

The modern Scoville scale is based on Wilbur Scoville’s Scoville organoleptic test, in which dried peppers were dissolved in alcohol to make an extract and then diluted in sugar water. The solution would then be continuously diluted and served to a panel of five taste testers until at least three of them could no longer detect any heat. In the organoleptic test, an SHU represented the highest dilution of the pepper extract in which the panel could still detect heat.

Because the organoleptic test relies on human subjectivity, pepper spiciness is now measured quantitatively via high-performance liquid chromatography (HPLC). This process divides the pepper into its separate components and measures the concentration of capsaicinoids (the compounds that create heat in fruits and vegetables) to determine how spicy a pepper is. HPLC measures spiciness in “pungency units,” but these units can be converted to SHUs.

How is Scoville Measured?

The simplest way to think about Scoville scale measurement is that the higher the SHUs of a pepper, the spicier it is. This is why a bell pepper, which is not spicy at all, has 0 SHUs, while an incredibly spicy habanero pepper can have anywhere between 100,000 - 350,000 SHUs.

Check out the chart below for an overview of how many Scoville units designate different spice levels.

 If you want a more scientific explanation of how peppers are measured on the Scoville scale, you’ll need to understand what exactly is being measured. Capsaicinoids are the components that give peppers their spiciness, and capsaicin is the most common capsaicinoid in chili peppers. 

In Wilbur’s original Scoville organoleptic test, SHUs measured how many times the capsaicinoid solution needed to be diluted for the taste testers to no longer detect heat. So, for example, a shishito pepper can have anywhere between 100 and 1,000 SHUs, meaning, it would need to be diluted 100 - 1,000 times before no spiciness could be detected.

Alternatively, HPLC, the primary test used today, measures the concentration of capsaicinoids in a pepper in pungency units, which are considered one part capsaicin (the most common capsaicinoid) per one million parts of dried pepper mass. These pungency units can be converted to SHUs (which are more commonly used) by multiplying the parts-per-million by 16.

What is the Hottest Pepper in the World?

The current world record holder for the hottest pepper in the world is the Carolina Reaper, which can be as hot as 2,200,000 SHUs. The Carolina Reaper obtained the world record back in 2013 with a 1,569,300 average Scoville rating, and the hottest pepper tested came back with a 2,200,000 Scoville rating. In 2017, the Carolina Reaper beat its own record with a new average Scoville rating of 1,641,183 SHUs.

While the Carolina Reaper is officially the hottest pepper in the world, other peppers have been grown that are said to be hotter. The Pepper X, created by the same man who developed the Carolina Reaper, is supposed to be twice as hot as the record holder, which would make it 3,180,000 SHUs; however, the Guinness World Records has not given an official word on this pepper and its supposed record-beating Scoville rating.

Another pepper that claims to be hotter than the Carolina Reaper is the Dragon’s Breath. This pepper has a reported Scoville level of 2,480,000 SHUs; however, like the Pepper X, the Guinness World Records does not recognize it as the hottest in the world.

Scoville Chart

Below is a chart that overviews the heat level and Scoville rating of various peppers. Keep in mind that each individual pepper can have different levels of spiciness due to a variety of factors, so Scoville units are typically listed in a range. 

FAQs

How many Scoville Heat Units is a ghost pepper?

A ghost pepper is one of the hottest peppers in the world and can range anywhere between 855,000 SHUs and 1,041,427 SHUs. In 2007, it won the Guinness World Record for the hottest pepper in the world until it was beat out by the Trinidad Scorpion Butch T in 2011.

How many Scoville Heat Units is a jalapeno?

A jalapeno pepper has a medium heat level with 2,500 - 8,000 Scoville units.

How many Scoville Heat Units is a habanero?

A habanero pepper is considered “extra hot” and can have anywhere between 100,000 - 350,000 SHUs.