Beer IBU

Beer enthusiasts know and often argue that there are various different perspectives we can approach and review a beer – its color, body, flavor, sweetness and bitterness. The last one is the one that brewers have been trying to find a way to properly measure, and the IBU scale was invented just for that. But what does a beer’s IBU mean? How accurate is the IBU scale? Let’s find out.

What is IBU?

IBU stands for International Bitterness (or Bittering) Unit. It was invented because brewers and drinkers wanted to know how bitter their beer was, but like anything subjective, “bitterness” was really hard to measure objectively. Thus, IBU was created.
A beer’s IBU is measured by calculating the alpha acids (namely, isohumulones) that get released from the hops during the brewing process. The amount of isohumulones released depends on the length of time boiled and the type and age of hops used. Isohumulones give a beer its bitter taste. And for the most part, IBU scale does a good job on giving us a general idea about a beer’s bitterness.
Almost every beer you drink will have an IBU score between zero and 120 (higher means more bitter), though there is not an upper limit to a beer’s IBU score. Flying Monkeys Craft Brewery in Ontario has the highest IBU beer known to man with “Alpha Fornication”, for example. But it is important to note that human tongue cannot sense IBUs higher than 110-120, so these extremely high numbers are usually used for commercial purposes.

Some popular examples to give you an idea about IBU would be Guinness Draught (45 IBU), Harp Premium Lager (21 IBU) and Breakfast Stout (60 IBU).

How Accurate is a Beer’s IBU?

What IBU scale does not take into account, however, is other elements that define a beer’s overall taste. You see, a beer is not just a bitter or not-bitter drink. Thanks to the infinite number of styles, flavors, brewing methods and such, we have an infinite number of different-tasting beer in our world, and simply measuring them between 0 and 120 is just impossible. Other factors such as a beer’s flavor and sweetness affect the bitter taste of a beer. It means that a 30 IBU beer with little flavor can taste significantly more bitter than a 60 IBU beer with a strong chocolate flavor, so IBU alone cannot measure perceived bitterness by itself.
This ambiguity caused beer enthusiasts to use a Gravity/IBU ratio chart. By gravity, we obviously do not mean the force that keeps your beer on your table. A beer’s gravity, simply speaking, refers to the number of dissolved solids in it. These solids are fermentable sugars. More fermentable sugar means more gravity, and more gravity means more bitterness masked. This chart isn’t perfect either, but it gives a much more accurate answer to our question.

So, do IBUs serve any other role other than being a general guideline for a beer’s bitterness and a marketing ploy for brewers? Well, it actually does.
Big manufacturers want their beers to be consistent. They do not want two bottles of the same beer tasting different. One of the ways they achieve that without human testing, which is unpractical for commercial brewers, is using the IBU scale. By testing their beers’ IBU, they assure that the huge amounts of beer they produce have the same overall quality.


So, as you can guess by now, no method of measurement can give us a definitive answer regarding to a beer’s bitterness, or general taste. The best method is and always will be, well, just tasting the beer. IBUs are great quality control tools for big brewers and serve as a general guideline for a beer’s bitterness, but that’s it. Just don’t rely on it too much before trying out a new beer.

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