IBU (International Bitterness Units)

IBU stands for International Bitterness Units and indicates the concentration of iso-alpha acids in beer, the bittering compounds from hops. One unit corresponds roughly to one milligram per litre. It is measured in a laboratory.

For rough orientation: mild wheat beers and Helles are often around 10 to 20 IBU, Pils usually 25 to 40, strongly hopped IPAs 40 to 70 or more. The figure alone does not tell the whole taste story: a sweet, malt-rich beer can seem less bitter than a dry one at the same IBU. Therefore the ratio of bitterness to original gravity matters. On labels IBU is mainly shown for craft beers.