Tea Brewing Calculator

Brewing tea is a selective extraction problem. The leaf of Camellia sinensis contains three groups of soluble compounds that behave differently: caffeine, which dissolves quickly and largely finishes extracting within three to four minutes; L-theanine and simple sugars, which give sweetness and a savoury umami character and come out readily even in cooler water; and catechins and other polyphenols, which convert to bitterness and astringency and dissolve much faster as temperature rises. Choosing a water temperature is therefore choosing a flavour balance rather than simply choosing how hot the drink will be. Delicate green and white teas are brewed at about 75 to 80 degrees C so theanine leads and catechins lag, while fully oxidised black teas and caffeine-free herbal tisanes take 95 to 100 degrees C because their compounds need the extra energy to release at all. The leaf-to-water ratio in Western brewing is around 2 to 3 grams per 240 ml, roughly one teaspoon, though weight is more reliable than volume because a fluffy white tea and a tightly rolled oolong occupy wildly different space at the same mass. Chinese gongfu brewing inverts the balance, using 5 to 8 grams per 100 to 150 ml with infusions of 10 to 30 seconds, which is why a good pu-erh can give 8 to 15 pours while a black tea gives one or two. Altitude matters because the boiling point of water falls roughly 0.5 degrees C per 150 metres of elevation, so at 3000 metres water tops out near 90 degrees C and black tea needs 15 to 30 extra seconds to compensate. Caffeine figures are estimates only: cultivar, harvest season, leaf grade, and processing all shift them substantially.

The first systematic account of tea preparation is the Cha Jing, or Classic of Tea, written by Lu Yu in Tang dynasty China around 760 to 780 CE. It is remarkable for how much of it concerns variables this calculator still uses: Lu Yu ranked water sources, described three visual stages of boiling by bubble size, and specified proportions of tea to water. Preparation methods then changed with the form of the tea itself. Song dynasty drinkers whisked powdered tea, a practice carried to Japan and preserved in the tea ceremony, while loose-leaf steeping became the Chinese norm after the Ming founder abolished the tribute of compressed tea cakes in 1391, which pushed producers toward whole-leaf styles and the small teapot. The attempt to fix brewing numerically is modern and British. The British Standards Institution published BS 6008 in 1980, adopted internationally as ISO 3103, defining a reproducible method for sensory comparison of teas: 2 grams of leaf per 100 ml of freshly boiled water in a specified porcelain pot, steeped exactly six minutes. The standard was never meant as advice for drinkers, only as a control so that tasting panels in different laboratories would produce comparable results, and its earnest precision earned it the 1999 Ig Nobel Prize in Literature. Consumer practice moved the other way, toward variability: variable-temperature electric kettles became common household equipment in the 2000s, and Western interest in gongfu-style short multiple infusions grew alongside the specialty loose-leaf trade, making per-type temperature and time targets ordinary rather than expert knowledge.