The Ultimate Guide to the Scoville Heat Scale

The Scoville Heat Scale - How hot is this chilli?!

The Scoville scale is a measurement of the pungency (spicy heat) of chili peppers—such as the jalapeño, the bhut jolokia, and the world's current hottest pepper, the Carolina Reaper—or other spicy foods as reported in Scoville heat units (SHU), a function of capsaicin concentration. Capsaicin is one of many related chemicals, collectively called capsaicinoids. The higher the SHU, the hotter the pepper or sauce is.

The scale is named after its creator, American pharmacist Wilbur Scoville. His method, devised in 1912, is known as the Scoville Organoleptic Test.

The Scoville Organoleptic Test

So how is the SHU score of a chilli pepper actually calculated?
The chilli peppers are first dried, and an alcohol extract of the capsaicin oil is then taken from the sample.
This extract is then mixed with a solution made of water and sugar until the 'heat' is barely detected by several taste-testers (humans).
The scored Scoville Heat Unit (SHU) of the pepper corresponds to how much the oil was diluted in the solution before the taste-testers can barely detect it.
So for example, a pepper or hot sauce with a SHU rating of 20,000 means that the capsaicin oil was diluted 20,000 times before the heat was detected.

This test is usually performed in laboratories and by a panel of taste-testers, which is both a costly exercise and the reason why not many hot sauce manufacturers send their sauce for testing.
The accuracy of the test is also subjective, since it uses "humans" as testers. Last but not least, chilli peppers may also have a variation of SHU ratings, even when taken from the same plant. So a first batch may be different to a second batch. The SHU rating can be influenced by the chilli plant's environmental conditions, such as temperature, humidity, soil type, age of the plant, seed lineage, etc

Scoville Heat Scale (updated 2018) & List of Chilli Peppers

Scoville Heat Scale (SHU)

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Scoville Heat Units Name of Peppers
0 Bell pepper
100 - 1,000 Banana pepper, Cubanelle, paprika, Pimento
1,000 - 3,500 Gochujang, Pasilla pepper, Peppadew, poblano (or ancho), Poblano verde, Rocotillo pepper, Espelette pepper, Mulato
3,500 - 10,000 Guajillo pepper, 'Fresno Chili' pepper, Jalapeño, wax (e.g. Hungarian wax pepper), Chipotle
10,000 - 30,000 Byadgi chilli, Serrano pepper, Peter pepper, Chile de árbol, Aleppo pepper, Chungyang Red Pepper, Peperoncino, Morita
30,000 - 50,000 Guntur chilli, Cayenne pepper, Ají pepper, Tabasco pepper, Capsicum chinense
50,000 - 100,000 Malagueta pepper, Chiltepin pepper, Piri piri, Pequin pepper, Siling Labuyo, Capsicum Apache
100,000 - 350,000 Habanero chilli, Scotch bonnet pepper, Datil pepper, Rocoto, Madame Jeanette, Peruvian White Habanero, Jamaican hot pepper, Fatalii Wiri Wiri, Bird's eye chili
350,000 - 580,000 Red Savina habanero
580,000 - 2,200,000 Komodo Dragon Chili Pepper, Trinidad Moruga Scorpion, Naga Viper pepper, Infinity Chilli, Naga Morich, Bhut jolokia (ghost pepper), Trinidad Scorpion Butch T pepper, Bedfordshire Super Naga, Spanish Naga Chili, Carolina Reaper (currently record-holder of the world's hottest pepper)
5,300,000 Police Grade Pepper Spray
16,000,000 Pure Capsaicin
16,000,000,000 Resiniferatoxin