The International Bitterness Units scale, or simply IBU scale, provides a measure of the bitterness of beer, which is provided by the hops used during brewing. An IBU is one part per million of isohumulone — the higher number, the greater the bitterness. Human taste sensory organs, called taste buds or gustatory calyculi, and concentrated on the upper surface of the tongue, appear to be receptive to relatively few chemical species as tastes. ... A selection of bottled beers A selection of cask beers Beer is the worlds oldest[1] and most popular[2] alcoholic beverage, selling more than 133 billion liters (35 billion gallons) per year - producing total global revenues of $331. ... Species Humulus lupulus L. Humulus japonicus Siebold & Zucc. ...

The bittering effect is less noticeable in beers with a high quantity of malt, so a higher IBU is needed in heavier beers to balance the flavor. For example, an Imperial Stout may have an IBU of 50, but will taste less bitter than an English Bitter with an IBU of 30, because the first beer uses much more malt than the second. The technical limit for IBU's is around 100, others have tried to surpass this number but there is no real gauge after 100 IBUs when it comes to taste threshold. Malted barley Malting is a process applied to cereal grains, in which the grains are made to germinate and then are quickly dried before the plant develops. ...

A light American lager might be as low as 5 on the scale, while a barley wine can range up to 100. Measures for other beverages include: (North) American lagers, as defined by the Association of Brewers, are a family of very pale to golden colored beers with light body and low to medium bitterness. ... Barley wine or Barleywine is a style of strong ale originating in England in the nineteenth century (derived from the March or October beers of the 18th century) but now brewed worldwide. ...

• Belgian Lambics: 11–23
• Blonde ale: 15–30
• Kölsch: 18–25
• Märzen/Oktoberfest: 18–25
• Ordinary English bitter: 20–35
• Porter: 20–40
• Brown ale: 15–25, with North American styles higher, 25–45
• Bohemian-style Pilsener: 30–45, sometimes it can range up to 100 (e.g. german Bitterpils)
• India Pale Ale: 40 or higher
• An Irish stout like Guinness: 45–60

A formula craft brewers use to calculate IBU is: Traditional wooden Lambic barrels; the L on the barrel indicates the brewery. ... North American blonde ales, also called golden ales range in color from that of straw to golden blond(e). ... Kranz of Kölsch Kölsch Kölsch is a local beer speciality brewed in Cologne, Germany. ... Märzen is a traditional bottom fermented Austrian Lager based on the Schwechater Lagerbier developed in 1837 by Anton Dreher. ... Motto (French) God and my right Anthem God Save the King (Queen) England() – on the European continent() – in the United Kingdom() Capital (and largest city) London (de facto) Official languages English (de facto) Government Constitutional monarchy  -  Queen Queen Elizabeth II  -  Prime Minister Tony Blair MP Unification  -  by Athelstan 967  Area... Bitter is a British term for a type of beer or pale ale. ... Å»ywiec Porter Porter is a style of beer in the ale family which has a dark colour. ... North American brown ales trace their heritage to American home brewing adaptations of certain northern English beers. ... World map showing North America A satellite composite image of North America. ... Flag of Bohemia Bohemia (Czech: ; German: ) is a historical region in central Europe, occupying the western and middle thirds of the Czech Republic. ... Pilsener or pilsner is a pale lager, developed in the city of Plzeň (Pilsen in German/English), Western Bohemia (now the Czech Republic). ... This article or section does not adequately cite its references or sources. ... A pint of stout Stout is a dark beer made using roasted malts or roast barley. ... Guinness logo World War II era advert. ...

W_h × AA% × U_aa ⁄ ( V_w × 1.34 ), where

• W_h refers to the weight of the hops used, in ounces
• AA% refers to the alpha acid percentage, which is influenced by many factors, including cultivation method, species, and time of year — hops are often sold labeled with this percentage
• U_aa is the percentage of alpha acid that is actually used during the boiling process
• V_w means the volume of the wort, in gallons
• 1.34 is a constant factor that adjusts the measurement to account for the use of U.S. customary units

There are several different methods for finding U_aa, which can yield very different results. Generally, U_aa increases with longer boiling times and decreases with higher boil density. The ounce is the name for a number of different units of mass (oz), and also of two units of fluid volume (fl oz) and of one unit of force, the ounce-force (ozf). ... Wort (IPA ) is the liquid extracted from the mashing process during the brewing of beer or whiskey. ... The gallon (abbreviation: gal) is a unit of volume. ... U.S. customary units, commonly known in the United States as English units or standard units, are units of measurement that are currently used in the U.S., in some cases alongside units from SI (the International System of Units—the modern metric system). ...

Further Reading: Explanation from Brew Your Own