The 100 IBU Ale: When 100 Doesn’t Mean What You Think It Means


As Americans, we have a thing about 100.

“100” indicates good, excellent, perfect, exceptional. 100 on your test is a perfect score. 100% means everything, all of it,  totality. 100 has become a milepost, a yardstick…and a horribly unreliable one at that. Beer is maybe the best example. “100 IBU” is derived from a measurement system based on the International Bittering Units, a loose worldwide agreement we all use to measure the hops content of any beer. But the deceptive part of that sentence is “hops content”. An IBU measures parts-per-million (ppm) of isohumulone, (the chemical compound in hops that balances out the malt sugars in your beer and keeps it from being cloyingly sweet) in some specified volume of brew. Isohumulone is infused into the liquid when alpha acids in hops isomerize (dissolve or break down) in the boil.  Isohumulones can also be added by hopping after the boil and that sometimes creates a more vivid and intense hop character. Hops were originally used in brewing because, as in ancient wines which were all sweet, humans got tired of sugary liquids and wanted something drier, that didn’t wear out its welcome quite so quickly. Many, many different plants were tried but hops, with their sticky, brutally aromatic, soluble resins, proved the most reliable, the easiest to cultivate, and gave the most harmonious flavors.

The Randall, just primed and ready

Beers that are under 100 IBUs have come to be regarded as less “serious” IPAs than those which manage to reach the magical triple digits. America has gone Hops Damned Crazy and, as with everything else we do in the USA, we have quickly embraced the idea of Excess in our India Pale Ales. (One technique, called a “Randall”, adds a last-second blast of hops by attaching a clear plastic cylinder, packed with whole hops flowers, and running beer through that as it pours into your glass!) While working in retail, I had on average, eight or ten customers a month (98% young men between 21 and 35) who came in and said flatly, “I don’t drink anything under 100 IBU.” No amount of explanation would budge them. Beers that were below 100 IBU were labeled “flabby” and dismissed out of hand. Breweries heard this. It became an outright rarity to find any brewery – especially here in the Pacific Northwest – that didn’t offer at least one or sometimes several IPAs that rated above 100 IBU.

Flying Monkeys “Alpha Fornication”

Because the Indie beer culture is so wildly dominated by young males, this Hops Arms Race became the modern equivalent to those old frat house “test of manhood” challenges.  Like chugging a bottle of Tabasco, eating a habanero or, back in the 1920s, eating a tarantula. (Yes, Grandpa was a FREAK).  The challenge became a test to see just how many IBUs you could tolerate without betraying the fact that the beer tasted like licking a pine tree and went down like acetone. Some breweries even tried creative interpretations of the IBU scale to “blow out” their bitterness claims. Flying Monkeys Brewing, of Barrie, Ontario brewed something called “Alpha Fornication” which they rated with a straight face at 2,500 IBUs. By means which I’m not going to divulge, I got a small sample of this monster. It looked like yellow pea soup, was opaque from sediment, and was exactly like cramming your mouth full of fresh-picked hops and sitting with that for an hour. Lord knows what the actual measurable IBU count was, but it was not even in the strictest sense of the word, beer. It was rough going and the aftertaste went on for nearly a full hour and completely swamped anything I used – from bread to chocolate to mouthwash – to get rid of it. But I drank it…so, to a certain group of young knuckleheads, I’m cool. (The only time in my life that has ever happened)

What all this manic IBU compulsion doesn’t take into consideration, at least with young beer freaks, is the amazingly variety of character we can enjoy from the the 50+  different hops that are commonly used in American Indie brewing. The original meaning of the term that sits in the center of the acronym IBU – “Bittering” – was intended in the original British sense: something used to balance out the malt sugars and to cut the sweetness, i.e., “bitter” the beer. It was not intended to measure actual tangible bitterness necessarily, but the amount of isohumulone content. And isohumulone is NOT just about bitterness.

Want proof? Find and chill a bottle each of Ninkasi Brewing “Tricerahops” and one of Moylan’s Brewing “Hopsickle”. Both these beers are rated by their brewers at 100 IBU. (NOTE: In certain years, IBUs for both can vary widely) Pop cap. Pour into glass. Taste, side by side.

These two beers are to each other as Honey Boo Boo is to Betty White. Both are fabulous beers. Both taste incredible and intense and unforgettable. But Tricerahops shows floral and citrus and spice flavors, with muted notes of the classic IPA profile of herbs and pine/spruce resins. Hopsickle tastes like your breakfast grapefruit, sprinkled liberally with rosemary, thyme, marjoram, and ground spruce needles. Tricerahops is milder and far more approachable for beer newbies. Hopsickle is a full-frontal, sinus-clearing Hops bombardment, a glorious tsunami of inspired, unrelenting bitterness that is absolutely thrilling, if you’re in the mood to be treated to a little zymurgical Tough Love.

How? They’re both 100 (and, in certain batches “100+”) IBUs. They’re both Imperial IPAs. Hopsickle, in fact, is listed, these days, as a Triple IPA.

The answer is the key to why measurements like 100 IBU really don’t mean much of anything.

There are dozens of different current varieties of hop flowers that are used in Indie brewing. These break down into bittering hops, aromatics, and flavor hops and they each do as the name says, even in the ones considered “dual purpose”. These two vastly different beers have their two primary hops in common: Chinook and Cascade. But the next three in each are totally different. In Hopsickle the assertive Simcoe, Columbus, and Ahtanum flowers are used for their bittering properties.  In Tricerahops, Summit, Centennial, and Palisade are brewed differently to showcase aromas of pepper, incense, apricot, grass, pink grapefruit, and jasmine with vivid flavors of anise, orange, pink grapefruit, lemon, spices, and tangerine. Both beers are complex but the hops are different and are used in different ways and in different quantities. Both have very similar amounts of isomerized isohumulone in the bottle but in totally discrete forms.

Hops, to nutshell all this, are NOT…JUST…BITTER. That is the shortest capsule description of why IBU ratings are inherently deceptive and don’t really indicate anything at all about how the beer will taste or even how bitter it will be. All this careful explication of how hops differ doesn’t even begin to take into account how brewers use hops and what effect that has on what they bring to the party. New hops are being hybridized literally monthly, and new techniques emerge just about as often. One of the latest is “hop bursting”, which is used to add massive hops in low-alcohol IPAs.  Also, the new method from Dogfish Head Brewing (Olde School Barleywine)  and Full Sail Brewing (Hop Shooter, just released) called “hop shooting”, which uses a pneumatic “hops cannon” to fire pelletized flowers into the tank from 35 feet overhead. I’m waiting for the development of the logical end of that idea, the Tactical Nuclear Warhead Hops Infuser, which creates a low-yield explosion in the tank and blows hops shrapnel out through the sides. If this shows up tomorrow, you’ll know I patented it.

With time, you will come to realize that you can hold a pint of Pacific Northwest Amber ale in your left hand (70 IBU) and a 100 IBU IIPA in your right from somewhere else in the US and find that the Amber is actually far more bitter than the IIPA. It’s true enough, to be basically routine.

Yeasts, water, grains…and hops. Those are really all that’s required to make any beer that deserves the name. It’s what we do with those and the thousands of other infusions and techniques that determine the actual character in your glass. In that sense, not only do IBU numbers offer NO idea of what the beer will be like, they frequently vastly understate the beer’s intensity and complexity.

Don’t be a chump. TASTE the beer before you go making a judgment. If you like the flavor, that’s a good beer – no matter what the IBU rating says.

Steve Body

Steve Body

Steve Body is a beverage writer who started as a straight journalist, with East Coast newspapers and magazines, and took a wrong turn about thirty years ago. He's been writing about beer since his college days and about wine and whiskey since 1999. He lives in Tacoma, Washington, freelances on subjects ranging from politics to food to real estate to laser-stream chromotography, and has a seven-pound terrier/chihuahua mix who farts and belches in his sleep.
Steve Body

3 thoughts on “The 100 IBU Ale: When 100 Doesn’t Mean What You Think It Means”

  1. I do agree that the IBU race is an old one.
    It’s impressive how fast this industry adapts and changes. Yesterday’s past trend was just a short 2 years ago,
    The current trend is IMO the chew NE IPA.
    Thankfully barrel aged stouts are still the rage.

  2. This is a bit outdated. It’s been years since I’ve seen breweries brag or compete about high IBUs. Also, the article suggests that isohumulone is the only iso alpha acid, but there are two others (isocohumulone and isoadhumulone). It also implies that dry hopping adds IBUs, but since the hops are not being heated up during dry hopping, there is no IBU contribution. Dry hopping adds aroma to beer, but not much bitterness. There is some bitterness added when beta acids oxidize, but that is not related to IBU.

    1. As with everything I write about beer – and anything I will write here – this post is NOT intended for the hard-core beer geek or homebrewer. This is a quick primer which may, I HOPE, pique somebody’s interest and allow them to dig into the subject of the post more deeply. In writing about the chemistry of beer or the technical aspects of brewing, I might lay out a comprehensive dissection of the whole process and other members of the isohumulone family but, here, I’m trying not to put the readers to sleep. If you want writing for beer geeks, I’m NOT your guy. The basic facts, here, are correct, so I’m fine with what I wrote. And, BTW, dry hopping certainly does bitter.


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