Remember IBUs? The “International Bitterness Unit” once appeared on beer labels and bar menus everywhere as the globally agreed-upon measurement for how bitter a brew is. But, as you may have noticed, it’s become an increasingly rare sight over the past few years. In fact, there’s a chance you didn’t see a single IBU in your last craft beer delivery, or store trip. 

There’s a reason for that, and it has a lot to do with how far craft beer has progressed.

What’s Up With IBUs in the First Place?

Beer bitterness comes primarily from the alpha acids in hops. Much of that gets lost when hops are boiled in the brewing process, so brewers developed the IBU scale in the 1950s and ‘60s to describe the estimated resulting portion of these alpha acids. Interestingly, you’ll find a wide range of IBU equations out there, and it’s worth noting that none of them are an exact science. That said, one of the most straightforward calculation methods is: Ounces x Alpha Acid x Percentage Utilization (the boil time) divided by 7.25 = IBU. 

Sound confusing? It is! A beer with a higher IBU is considered more bitter than one with a lower IBU, but that’s not necessarily true with today’s high malt contents or other ingredients that smooth out the bite. Wise Man Brewing’s Outraged Daughters Irish Red Ale has a mid-range 25 IBU, though only the slightest hint of hop bitterness is apparent between its mellow caramel and dark fruit-like malts. Meanwhile, Gnarly Barley Brewing’s Peanut Butter Korova Milk Porter sits at 20 IBU, though the peanut butter additions combine with the mocha malt base to create a brew far smoother than other Porters clocking in at the same measured bitterness level. 

In fact, IBUs have become so non-indicative of how bitter today’s craft beers taste, the Brewers Association now states they “will not consistently coincide with an individual’s perception of bitterness intensity.”

The IBU vs. the Modern IPA

The flexibility of today’s IPAs present another issue for IBUs. About a decade ago, more hops meant more bitterness and, therefore, a higher IBU. Clean-sipping, defiantly bitter West Coast-style IPAs like Burial Beer Co.’s Surf Wax exemplify the earlier hopbombs that paved the way for so many of today’s immensely flavorful styles. Surf Wax itself boasts a massive 68 IBU and four different kinds of hops.

Nevertheless, today’s IPAs come in a wide berth of sub-styles, from the sweet ‘n thick Milkshake IPA to the lush, Juicy IPA. In fact, current Brewers Association guidelines for the ‘Juicy or Hazy IPA’ explicitly state that, while the expected IBU for the style falls between 20 and 40, the number can vary greatly outside of that. Adroit Theory’s Evangelion XIII: Bardiel Edition Hazy Triple IPA, for instance, clocks in at a crazy 65 IBU. Even so, it sips down creamy and smooth, thanks to masterful double dry-hopping that coaxes out pillowy juice flavors from five different hops. 

Then there are beers like Truck Chaser Strawberry Eclair IPA from Wild Leap Brew Co. It has a 49 IBU, but any traces of bitterness in this Juicy IPA are deliciously masked behind lactose, vanilla, and real fruit additions.

Will We See the IBU in the Future?

It’s also worth noting that as craft beer has progressed, so has science. Human genetics are now understood to play a big role in how bitter flavors are processed. So, what your buddy perceives to be “a super bitter IPA,” you may find more smooth and flavorful. 

In all likelihood though, brewers will continue to use IBUs as a unit of measurement during the brewing process to maintain consistency between beer batches. That doesn’t mean they’ll keep putting them on labels or menus. Some of the nation’s most sought-after breweries, like Anchorage Brewing, no longer post their beer IBUs regularly online.

On the beer drinker’s end, there are simply far better indicators – like the style, ingredients, and ABV – that suggest how a beer will taste. So, you might want to save some of those labels that list the IBU now. They may very well be relics one day!