IBU, or International Bitterness Units, if that number you see on tap signs, on the side of your beer can, and the thing you hear your hop head friend bragging about as he sips the latest double IPA. While we might all guess that based on the name it has something to do with how bitter the beer is - what does IBU really mean and how does it affect the taste of your beer, the style of beer, and everything else?
If we want to get technical, IBU measures the parts per million of isohumulones and other chemical compounds in a particular beer, which make up the acids found in hops that gives beer its bitter taste. However, there are a number of factors that go into how “bitter” a beer is and sometimes what is listed as a beer’s IBU, while scientifically accurate, this isn’t the whole story. A beer with a large malt profile, while also high in IBU, could be way less bitter and hop forward than a beer with a lower IBU that also a smaller malt profile. There’s also the element of extra added ingredients, such as coffee, spices, or fruit, that could give a higher or lower perceived bitterness while not affecting the IBU of the beer.
So why the heck do we use this scale if it isn’t even accurate to taste? Well, because we are humans and we like to categorize things, but also it generally helps the consumer get a better idea of how the beer is going to taste when they order it. While knowing styles and other factors is also important, a person who generally goes for Porters and Stouts which have a lower IBU and a low amount of hops in the beer is going to know that they probably shouldn’t order the IPA on the menu with an IBU of 75. The IBU scale generally starts at 5 and ends around 120, however the IBU limit is infinite and I’m sure there will be plenty of brewers trying to push the envelope in the future as the trend of bigger and bolder beers continues to grow.
While IBU helps give the beer drinker clues about what they’re about to drink, it also helps the brewers know that they are on track when brewing different styles of beer or producing large amounts of one of their mainstay beers. If the IBUs are out of whack or not what they’re expecting, they know that something has gone wrong and it’s time to go back to the drawing board. So while IBU might not tell you everything you want to know about your beer and the true bitterness of your brew is variable depending on other factors, it is an important tool for both the consumer and maker of the beer and it can help you up your beer knowledge as a whole making you seem smarter and way more cool in front of all of your friends.