International Bittering Units don’t tell the beer’s whole story


I have been heartened and impressed by the rapid growth in consumers’ beer knowledge over the past couple of years. People really are starting to understand what craft beer is about—so much so, in fact, that I’ve noticed certain concepts and terms—which were the solitary purview of beer geeks only a few years ago—entering the general vernacular.

Case in point: IBUs.

IBUs is the acronym for International Bittering Units. It is the standard for measuring the amount of bitterness in a beer and was created by scientists in the 1960s to find a way to consistently measure beer bitterness. It was treated as a strictly technical measure, to help in recipe formulation and quality control.

More recently, ardent hopheads have embraced it to help them seek out increasingly hoppier beers. And that is where things took a turn for the worse. Today, I find those three letters everywhere: on bottle labels, in ads, on beer-bar menus and, increasingly, on the lips of beer-curious consumers.

I have mixed feelings about this turn of events. On one hand, I am thrilled consumers are learning about the technical details of beer and integrating it into their appreciation of it. On the other hand, I also find the term being misused and misunderstood.

Allow me to explain. IBUs is a calculated number that represents the amount of alpha acids (the bittering agent found in hops) that have absorbed into the beer. A standard North American pale lager might run 10 to 15 IBUs. American pale ale will hit around 40 to 50, while a hoppy India Pale Ale will reach 70 or so. The biggest, hoppiest beers will close in on 100 IBUs.

It sounds simple, except it’s not—and that is why the term is being misunderstood. People are under the misguided impression that knowing the IBU number actually tells you something meaningful about the beer—but it doesn’t.

First, there is no context to the number. Say the labels reads 40 IBUs. What exactly does that mean? Is that a lot? Is it low? What will it mean for what I taste? The number on its own is not useful.

Second, the number being provided is almost always what’s called “calculated” IBUs, which is the number estimated before brewing. Actual IBUs can only be measured in a laboratory after the fact. There can be a big difference between calculated and actual IBUs because the science behind bitterness extraction is very complex. There are many factors that will affect how bitter the beer actually becomes, including the alcohol strength of the beer, the types of acids found in the hop and even the size and shape of the brew kettle. What you taste might actually be quite different than what the label says.

Third, and most importantly, bitterness is only one flavour component of beer. Our perception of bitter is also affected by the other ingredients in the beer. Sweetness from malt counters our perception of bitterness, so increasing the malt character of a beer will make it seem less bitter, even if the total number of IBUs remains unchanged.

Let me clarify with an example. American Pale Ales are noted for being bitter and hop-forward and have between 40 and 50 IBUs. Now, guess how many IBUs are found in an inky black Irish stout, which is all about the malt? Forty to 50 IBUs. All that extra malt body and sweetness in the stout needs more hops to keep the beer in balance. So the number of IBUs tells us very little about what the beer actually tastes like.

Rattling off the IBU number in isolation tells you almost nothing about the beer, unless it is accompanied by other statistics, such as style, colour, alcohol, final gravity and so on. It only tells part of the story—and a fairly small part, at that.

Go ahead, beer drinkers: embrace new terms like IBUs. Just make sure you have a full understanding of exactly what they mean to what you’re tasting. V

Jason Foster is the creator of, a website devoted to news and views on beer from the prairies and beyond.

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