What scale measures the pungency or heat of chili peppers?

The scale that measures the pungency or heat of chili peppers is the Scoville scale.

American pharmacist Wilbur Scoville developed the method in 1912. His original Scoville organoleptic test diluted pepper extract in sugar water until trained tasters could no longer detect its heat. The result was expressed in Scoville heat units, or SHU.

The heat comes mainly from capsaicinoids, especially capsaicin, which activate pain-and-heat receptors rather than literally raising the pepper’s temperature. Modern laboratories generally use high-performance liquid chromatography to measure these compounds more objectively than taste panels.

The scale is not perfectly fixed: a pepper’s rating can vary with variety, growing conditions, ripeness, moisture, and testing method. A bell pepper measures about 0 SHU, while some exceptionally hot peppers exceed 2 million SHU. The Mohs scale measures mineral hardness, Beaufort measures wind force, and Brix measures soluble sugar concentration.