What are IBUs?

In my beer session for Surly Furious yesterday, I mentioned the beer had 99 IBUs. Then I realized some of you might be wondering, "What are IBUs?"

IBU stands for International Bittering Units. It is a scientific measure of the bitterness of a beer. What is measured to come up with the number of IBUs, you ask? Well, when you add hops to beer, they contribute some acids that make the beer bitter. These acids are measured in parts per million to come up with the number of IBUs.

IBUs are physical measure of bitterness, but I believe that your tastebuds are a better judge. Hops will add bitterness to beer, but malt can balance it out. If a beer has higher IBUs, its final perceived bitterness will be determined by what kind and how much malt was used.

Lets say 2 different beers have the same 65 IBUs. If one recipe used a small amount of pale malt, you'll notice the bitterness more. If there was a massive amount of caramel malt in the other recipe, you might not think it tastes that bitter even though it has the same measure of IBUs.

Malt sweetness and hop bitterness. It's all about balance. Don't let IBUs scare you. Your personal taste will tell the whole story!