What exactly is IBUs in beer?

Let’s look at a well-known, yet little understood way of measuring how bitter a beer is. IBUs are often thrown around as a trendy stat on product labels and beer descriptions. They’re a very relevant way of measuring certain aspects of a beer’s flavor and aroma. They do not (in any way) make a beer better or worse. It’s all about matching your preferences to the measurable facts about a beer to find that perfect sweet spot for you.

What is an IBU?

International Bitterness (or “Bittering”) Unit
IBUs were invented because it was hard to measure how “bitter” a beer was like it’s hard to measure. It was all about perception.

International Bitterness Units are a chemical measurement of the number of bittering compounds, isomerized and oxidized alpha acids, polyphenols, and a few other select bittering chemicals that make your beer taste bitter. The IBU correlates well, in most cases, with the sensory bitterness of beer, and this is why brewers use it. Almost all the beer you’ll ever drink will have a measured IBU between 5 (which is a very low measured bitterness) up to 120 (which is a very high measured bitterness). Most beer falls in a narrower range within these parameters (between 15-80ish), but that’s the gist of it

We want to be clear on something though. Beer is about the balance of ingredients and taste. because a beer has a higher IBU doesn’t mean it is perceived (or tastes) to be as bitter as something with a lower IBU. You can drink a strong Amber ale rated to 60 IBU that doesn’t taste as bitter as a 55 IBU Pale Ale. The stronger malt flavor of the Amber ale matches the IBU’s of the beer and balances them. The IBU scale measures the number of chemicals in a beer that makes it taste bitter. Make sense?

IBU’s are generally indicative of how bitter a beer will taste. Generally speaking, the more IBU’s, the more bitter it will taste.

History of IBUs

People have been brewing beer in one form or another since biblical times. Ancient brewing recipes often incorporated herbs and spices to flavor the beer, while more modern recipes rely on hops. Beer brewed with hops has a wonderful variety of flavors and a longer shelf life than other brewing methods.

Brewers have been using different varieties of hops to brew beers for around 200 years. Hops or the flowering part of the hop plant is used for brewing beer and herbal medicines. When brewing beer, the different varieties impart different flavors like floral, fruity, or citrus notes onto the brew. The hops contain a high amount of alpha acids that break down into bittering agents during the fermentation process.

It is not an exact science, and many variables can change the way a beer tastes, but generally speaking – more hops means a stronger bitter flavor. Different varieties of hops also contain different alpha acid levels. Some being used for bittering and others for flavor or aroma.

The IBU Scale

IBU Scale Example in Beer Style

International Bitterness Units are measured on a scale from 0 to….infinity. There’s no ceiling on the IBU scale because you could make a beer more and more bitter without an end in sight. There’s a limit on how many IBU’s a beer can have because there is a physical limit on how many of these bittering compounds you can shove into a glass of beer. There are documented beers that have rated to over 1000 IBU’s, but it’s rare to see anything that high.

Almost all the beer you’re ever going to drink will have an IBU rating between 5 and 120. 5 has a very low measured bitterness and 120 having a very high measured bitterness. 

We’re not going to get into the science of how this is actually measured. IBU measurement involves spectrometers, isooctanes, industrial-grade acids, and complicated/expensive machinery like centrifuges.

Commercial breweries have this equipment, and measure IBUs, as a quality control tool. They make a large quantity of the same beer, and they want to make sure the beer tastes the same every time. Quality control is a huge part of brewing. And the IBU measurement quantifies the bitterness of the beer their brewing, allowing them to put out a consistent product.

In conclusion…IBU’s are a great way to measure a very specific aspect of your beer. They do not state flavor, aroma, perceived bitterness, or any other factor that allows you to enjoy the beer you drink. But IBU’s are part of the industry, and it’s worth knowing a little more about them. As you drink more beer and hear their IBU counts, you can start to find the zone you generally prefer and help build your own beer palate.

BONUS: Maximum IBU (mIBU) in Beer

These days, the IBU scale is no longer a true representative of the bitterness in modern-day beers. This is because hops used in the 20th century were often already oxidized due to the poorer processing, packaging, and storage methods.
Our recommended way of calculating IBUs is using the mIBU calculation that was developed by Paul-John Hosom in 2015. Maximum IBU (or mIBU) is a modification of the Tinseth IBU formula. It includes many optimizations that are better suited for the beers we brew today. 

mIBU measures post-boil bitterness contributions by more equipment and processes. It includes kettle diameter, cooling method, hop stand process and hop temperature. This results in a more accurate prediction of IBU contribution over time.

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