When you order a beer or pick up a case, you will find that many bottles or cans list an International Bitterness Units (IBU) value. The IBU is a measure of the bitterness in a beer and is usually expressed as parts per million (PPM). Generally speaking, beers with higher IBUs are more bitter than those that have lower numbers. A good way to think about it is on the same lines as spice levels in food. The higher the number, the more intense the taste profile of the beer will be. Although it can be difficult to measure sensory experiences like bitterness, the IBUs have provided a reliable way of assessing just how bitter a beer is since they were invented in the early 20th century. While these experiences are relative and subjective, IBUs make it possible to put a number on this perception. This metric has continued to evolve over time, allowing brewers to determine easily how their craft differs from others. What is an IBU used for? The bitterness of beer may not be the most obvious ingredient, but it plays a pivotal role in creating a balanced and cohesive product. The IBU is used to indicate just how bitter each specific beer is as it measures the concentration of any compounds responsible for causing bitterness on the tongue. This process is quite complicated and requires highly precise scientific equipment to carry out successfully, but understanding the implications of how IBU works is far simpler. A low IBU rating usually indicates a milder beer without any harsh notes. Beers with higher IBUs, in the range of 10-80 for example, are more commonly found in restaurants and bars. While extreme examples exist at either end of the spectrum, anything over 120 IBU is considered to be beyond what can reasonably be tasted in a single sip. What is an IBU’s importance? While the IBU scale gives us an indication of what to expect from the bitterness of the beer, it doesn’t necessarily tell the whole story. The balance between malt and hop ingredients ultimately determines how bitter a beer will taste- regardless of its IBU rating. A good example of this is an amber ale with higher IBU content than many pale ales. But, that doesn’t necessarily mean it is more bitter or better in taste. The maltiness of the amber ale compensates for the higher IBU rating creating a balanced beer. It’s important to consider not only IBUs when determining a beer’s bitterness levels. Rather, consider other ingredients to ensure you get exactly what you’re looking for. Our sense of taste takes into account multiple factors while perceiving flavors in our drink. It is essential to have an understanding of any other potential contributing agents. It might provide insight into how bitter a beer may ultimately taste. In summary, IBU serves as a great starting point for estimation purposes. However, it does not necessarily provide an end-all-be-all measure of how bitter a beer might taste.