With the recent crowning of Pepper X as the new Guinness World Record holder for hottest chili pepper, here's a look into just how the spiciness of a pepper is calculated — and some examples of very hot chilis for food daredevils to enjoy. 

Spice in peppers is measured in something called Scoville Heat Units, which basically calculates the concentration of a chemical compound called capsaicinoids. Capsaicinoids are found in the white lining of a pepper, said the National Institute of Standards and Technology (NIST) website.

First developed over a century ago by pharmacologist Wilbur Scoville, the Scoville Scale measures peppers from a scale of 0 (no spice whatsoever) to the current record of 2.693 million (very, very, very spicy). 

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At the time it was first developed, the Scoville Scale was tested by "extracting the capsaicinoids from a pepper and diluting them with a solution of sugar and water until the heat of the pepper [could] no longer be tasted by a panel of professionally trained taste testers," said the NIST.

The more a sample needed to be diluted, the higher its concentration of capsaicinoids — and the spicier the pepper, said NIST. 

Man holding Guinness World Record certificate

Ed Currie of South Carolina holds up his certification that his new Pepper X variety of peppers is the hottest in the world, according to the Guinness Book of World Records. He has held the record several times in the past for other pepper creations. (AP Photo/Jeffrey Collins)

Today, this process no longer requires human taste testers and is done entirely in a lab. 

Read on for some of the spiciest peppers a person can buy.

1. Pepper X

Yup, that's literally the name. 

Creator Ed Currie and his team at Puckerbutt Pepper Company in South Carolina decided that Pepper X — originally chosen as a placeholder name — just kind of worked for their newest hybrid hot pepper. 

Coming in at a whopping 2,693,000 SHU, the newly crowned Guinness World Record holder for "hottest chili pepper" is about three times as hot as the former champion. 

An orange and green pepper that is very small

A Pepper X pepper. This pepper is the newly crowned Guinness World Record holder for "hottest chili pepper."  (AP Photo/Jeffrey Collins)

Created as a blend of the Carolina Reaper and a mysterious "brutally hot" pepper from Michigan, Pepper X is not for the faint of heart.

In fact, it has a higher SHU rating than police-issue pepper spray and bear spray, reported the Associated Press. 

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2. Carolina Reaper

The previous world record holder is also a creation of Currie and Puckerbutt Pepper Company.  

"To breed these things, I crossed a ghost pepper with a habanero, and what came out was this evil-looking pepper that had warts all over it, blisters, they call them," said Currie in a 2017 video called "Breeding the World’s Hottest Pepper."

carolina reaper pepper

The Carolina Reaper, also a creation of Ed Currie, was the previous Guinness World Record holder.  (AP Photo/Jeffrey Collins)

The first time Currie tasted one, it "knocked me to my knees," he said. 

They average about 1,640,000 SHU.

The Guinness Book of World Records recognized the Carolina Reaper as the hottest chili pepper in November 2013. The Carolina Reaper broke its own record in 2018. 

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3. Trinidad Scorpion varieties 

As the name suggests, Trinidad Scorpion peppers come from Trinidad, and are so named because their tails resemble a scorpion's stinger. 

While the Trinidad Scorpion pepper comes in at a (comparatively) tame 300,000 SHU, varieties of this pepper have set records, says the website Chili Pepper Madness. 

Unlike the Carolina Reaper and Pepper X peppers, some Trinidad Scorpion peppers are indigenous and are not hybrid plants created by pepper enthusiasts. 

a red chili on a plant

The Trinidad Scorpion pepper was named after its tail, which resembles a scorpion's stinger. (iStock)

The naturally-growing Trinidad Moruga Scorpion peppers are some of the hottest on earth, the Chili Pepper Institute at New Mexico State University found, with an individual pepper coming in at over 2 million SHU. 

These peppers are found near the town of Moruga, Trinidad and are named after the town. 

A hybrid variety of the Trinidad Scorpion, the Trinidad Scorpion Butch T Pepper, was grown in Australia and was also a Guinness World Record holder before it was unseated by the Carolina Reaper.

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4. Ghost Pepper

Originally known as Bhut Jolokia, the pepper got its English name by a translation mistake. First cultivated in Assam, India, the name directly translates to "Bhutanese Pepper," says the website HowStuffWorks.

In Assamese, the word "Bhut," meaning Bhutanese, sounds similar to the word for "ghost," leading this terrifyingly spicy pepper getting its new name. 

A pile of ghost peppers

Ghost peppers were the first pepper to break 1,000,000 on the Scoville scale. (Anuwar Hazarika/NurPhoto via Getty Images)

This hybrid pepper is a combination of a habanero-type pepper and a pepper similar to tobacco or birds eye. 

Ghost peppers were the first peppers to break 1 million SHU. In 2007, the Guinness Book of World Records recognized the ghost pepper as the hottest chili pepper.

Since then, ghost peppers have made their way into the mainstream, even appearing on fast food chains' menus. 

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5. Chocolate Habanero

Don't be fooled by the name (or the color): This pepper is anything but sweet. 

Instead, the name comes from the deep brown color of the pepper, which resembles the color of dark chocolate. 

dark brown peppers

The chocolate habanero is one of the spiciest varieties of habanero peppers. (iStock)

Even among habanero peppers, which are some of the spiciest naturally occurring peppers, chocolate habaneros are at the upper level of spice, says the website "Grow Hot Peppers." 

They range from 400,000 to over 500,000 SHU. 

An orange habanero pepper, by comparison, maxes out at about 325,000 SHU. 

These peppers "have a distinct earthy and somewhat smoky taste," said Grow Hot Peppers.  

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Unlike hybrid peppers, which are a combination of two different kinds of peppers, chocolate habaneros were selectively bred from other habanero peppers for their size and spice. 

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