Beer really all boils down to three main components: the malt, the yeast and the hops. Within these broad categories there are, of course, worlds of flavor to enjoy. But ultimately it’s all about the fundamental characteristics and combinations of these three constituents. Today let’s concentrate on that magical budding flower that has been used for hundreds of years as the primary bittering agent of beer: hops.

If you really want to get technical, you could take a whole chemistry class on the isomerized alpha acids present in hoppy resin that ultimately produces that lip-puckering bitterness that has been likened to rusty tin. But let’s keep it simple here and just zero in on a relatively easy matrix that has been established in order to help us assess the relative hoppiness of any beer: International Bitterness Units, or IBUs. This measurement is essential in understanding the fundamental flavors of your beer before you even open the bottle. Technically, the scale goes from zero to infinity. But since we can’t really perceive bitterness beyond a certain threshold, the practical limit to IBUs is somewhere just over 100.

It’s fairly likely that if you fancy yourself a devoted ‘hophead’ you’re going to be thoroughly pleased with any beer approaching triple-digit IBUs. However, the IBUs don’t always convey the whole story. Since we all have varying tastes, it would be damn near impossible to take an objective calculation of flavor. IBUs are actually a quantified measurement of how many isomerized alpha acids are in the particular beer. But these bitter particles can be camouflaged by other ingredients in the mix. Namely: the malt and the yeast. If the beer in question has a significantly high IBU, it might still have a mellow finish thanks to a relatively high presence of malt, and perhaps even some super strong, flavorful yeasts.

So IBUs often tell a compelling story, but not always the full story. That being said, the next time you come across a beer that has 100 IBUs or more, the chances are real good that you’re in for an explosion of bitterness. Don’t be surprised, however, if it’s at all bittersweet.