What is IBU on beer?

What does IBU stand for?

If you're wondering how bitter your beer is, the IBU will give you some indication. It tries to be an objective way to estimate the potential bitterness of beer.

But don't get your hopes up, IBU's values are to give you a general sense of the bitterness of beer. Still, even if your beer's IBU number is set in stone, you can still control bitterness.

How Does the IBU Scale Work?

One IBU is equivalent to 1 part per million of isohumulone. The lower end of the scale estimates a lower bitterness for your beer and vice versa. To be clear, it does not guarantee the actual bitterness you will experience.

Isohumulone is better known as “Iso Alpha Acid” (IAA) or just alpha acid.

What Is the IBU Range for Beer?

The typical IBU range of beers is 0 to 120. Below is a table of some styles for you to get a general idea.

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What Is the Difference Between IBU and ABV?

ABV and IBU are measures of very different things from very different sources.  ABV is an assessment of a beer’s strength in terms of the amount of alcohol in your beer. While IBU is an estimate of bitterness through a certain chemical in your beer that came from hops.

ABV is more intuitive than IBU because, from the angle of a consumer, most IBU predictions suck. Especially with all the flavored beers out and about.

Can a Beer Have 0 IBU?

If you happen to dislike hops, you can make a zero IBU beer. In ancient and medieval times, people used “gruit” for their bittering agent. Gruit is a combination of herbs and spices that historically used to do the job of hops. If you go for that old-school style, you can easily hit a zero.

Also, if you add hops in your wort outside of the boil, you have better chances of zero changes to IBU.

How Do You Measure IBU in Beer?

If you are a small brewer, UV spectrophotometry is your best choice. Trained panelists are good as well but it depends on what you value. If you want to focus on quality control and consistency, go for spectrophotometry. If you value customer satisfaction, focus groups are worth the effort.

As a bonus, below is the general idea of UV spectrophotometry for the scientists out there:

• Take out your samples of beer.

• Place them in vials.

• Pour in carefully some hydrochloric acid.

• Pour in carefully an organic solvent.

• The isohumulones will gravitate to the solvent.

• Separate the emulsion formed and draw off the solvent into your cuvette.

• Pass a beam of 275 nanometer-wavelength light.

• Measure the absorbance and calculate the IBU.

How to Calculate IBU Beer

There are two ways to calculate IBU. First, after doing the spectrophotometry, multiply the absorbance by a factor of 50. Simple and easy, for a scientist, that is.

Second, if you want to make a quick estimate, try this empirical formula from Fred Eckhardt. By the way, he is the pioneer of beer journalism.

• IBU = the Sum of Ounces of Hops multiplied by the Alpha Acid Content of the Hops multiplied by the % Hops Utilization divided by a constant 7.25.

• IBU = Σ [(Ounce of Hops) x (% Alpha Acid) x (% Hops Utilization)] ÷ 7.25

Below is a table of Hops Utilization for the above formula:

What Affects IBU?

What affects IBU by value are the boiling parameters of hops, and diluting your beer in any way. Stuff that affects IBU by quality is on quite a long list:

• Water Chemistry

• Intensity of Grain Roast

• Unconverted Sugars

• Secondary Hop Chemicals

• Herbs and Spices

• Sweeteners (Artificial or Natural Juices, Fruits)

• Carbonation