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Homebrewing Articles
Written by Michael Korbel on May 22, 2011.

HBU’s (homebrew bitterness units) are actually very simple. HBU equals the percent alpha acid of hops multiplied by the quantity in ounces of hops used. For example:

  • 1 oz @ 5% = 5 HBU.
  • 2 oz @ 5% = 10 HBU
  • 2 oz @ 4% = 8 HBU
  • .5 oz @ 8% = 4 HBU

Lets say you have a recipe which calls for 10 HBU Cascade hops and you only have Columbus hops on hand…both having different alpha-acid levels, you could do the simple math to interchange them. Lets say (just for the sake of this tutorial) that the Columbus hops have 4% alpha acid, and that the Cascade called for in the recipe had 5%.

10 HBU Cascade = 10(HBU) / 5(Alpha Acid Content) = 2 ounces Cascade
10 HBU Columbus = 10(HBU) / 4(Alpha Acid Content) = 2.5 ounces Columbus

Or lets say you wanted to use something much more bitter, or you are trying to imitate the hops from the famous Founders Centennial IPA. Lets assume you still need only 10 HBU (for the sake of the tutorial…), and you only have Centennial hops on hand which have an alpha-acid content of 11%.

10 HBU Centennial = 10(HBU) / 11(Alpha Acid Content) = .9 ounces Centennial

Once you get the hang of the math, its easy to do without even looking back at these tutorials. For those who are less math inclined, you may need a sheet of paper and a pencil. Many homebrewers state the amount of hops in terms of total HBU’s of a certain hop variety, where as others will just give you the amount of hops they used, and how much their alpha acid content was. Given this information the HBU’s can be determined very easily. Some recipes will only give you the amount of hops in ounces…Say 2.5 ounces Chinook hops @ 60 minutes. This is an incomplete recipe and will be hard to follow exactly because we have no idea the alpha acid content in the Chinook hops, therefor making HBU’s impossible to determine. Each year the values could be slightly different. Generally the alpha acid content in hops fall within a range of values.

As your brewing skills progress, you should ditch the HBU’s and start using IBU’s. Check out our article here.

Works Cited: 

  • Pyle, Norm. “Norm Pyle’s Hops FAQ.” 1995. 18 Feb. 2009 .
  • Wortmonger. “Utilization.” Home Brewing Wiki. 2008. 18 Feb. 2009 .
  • Nachel, Marty. Homebrewing for Dummies. New Jersey: Wiley Publishing Inc, 2008.
  • “Glenn’s Hop Utilization Numbers” 1999. 20 February. 2009.
  • “Comparing Alpha Acid Utilization Formulas” The Draught Notice. 8 Jan 1998. 20 February. 2009.
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