Yes, barley is the primary grain in the vast majority of beers. It serves as the main source of fermentable sugar, which yeast converts into alcohol and carbon dioxide. In many classic beer styles, barley malt makes up 75% or more of the grain bill, with some styles using 100% barley and nothing else.
Why Brewers Rely on Barley
Barley earned its place in brewing because of its unique chemistry. When barley is malted (a process we’ll get to shortly), it develops powerful enzymes that break starch down into simple sugars. The most important of these enzymes drives what brewers call “diastatic power,” essentially the grain’s ability to convert its own starch into fermentable material. No other common grain does this as efficiently, which is why barley has been the backbone of beer for centuries.
Barley also has a physical advantage: its husk. After the sugars are extracted during brewing, the leftover husks form a natural filter bed that lets the sweet liquid drain cleanly away from the grain. Other grains like wheat and oats lack this sturdy husk, which is one reason they’re typically used alongside barley rather than on their own.
How Barley Becomes Malt
Raw barley kernels can’t go straight into beer. They first need to be malted, a controlled process with three main stages: steeping, germination, and kilning. During steeping, the grain absorbs water. It then begins to sprout during germination, which activates the starch-converting enzymes brewers need. Kilning stops the sprouting by drying the grain down to about 5% moisture.
The kilning stage is also where flavor and color develop. In the final hours, temperatures rise above 80°C (176°F), triggering chemical reactions between sugars and amino acids known as Maillard reactions. Lightly kilned malt stays pale and produces the golden color you see in pilsners and lagers. Longer or hotter kilning creates darker malts with roasted, caramel, or chocolate-like flavors used in porters and stouts. The same barley can produce dramatically different beers depending on how it’s malted.
Two-Row vs. Six-Row Barley
Brewers choose between two main types of barley, named for the arrangement of kernels on the stalk. Two-row barley has larger, more uniform kernels with more starch relative to husk, making it the preferred choice for all-malt beers. Most craft brewers and European breweries favor two-row for its cleaner, more consistent sugar extraction.
Six-row barley has smaller kernels with proportionally more protein and higher enzyme activity. That extra enzyme power makes six-row popular with large North American breweries that brew with adjuncts like rice or corn, since those grains lack the enzymes to convert their own starch. The six-row barley does the heavy lifting for them. Six-row’s higher protein also makes it useful for specialty malts, where amino acids contribute to color and flavor development. You probably wouldn’t want to brew a beer with nothing but six-row, though. Too much protein (above roughly 5.5% in the liquid) can cause haze, filtration problems, and unwanted color changes during boiling.
How Much Barley Is in Different Beer Styles
The percentage of barley varies widely depending on the style. German-style lagers follow strict traditions rooted in the 1516 Bavarian Purity Law, which decreed that only barley, hops, and water could be used to brew beer. (Yeast wasn’t added to the approved list until 1906, since its role in fermentation wasn’t yet understood.) For bottom-fermented beers, modern German law still requires malted barley as the sole grain. German brewers remain bound by these rules today, even though imported beers sold in Germany don’t have to comply.
American-style lagers and pilsners commonly use up to 25% rice or corn alongside barley. Some rice lagers contain 15% or more rice in the grain bill, with barley filling out the rest. Wheat beers require at least 30% malted wheat by definition, but barley still provides the remaining 70%. Even in a style like Kentucky Common Beer, which historically used 25 to 35% corn, barley malt remained the majority grain.
Barley and Gluten
If you’re searching whether barley is in beer because of gluten concerns, the short answer is that standard beer contains gluten. Barley’s storage proteins, called hordeins, are part of the gluten family. Research published in PLOS One found that all barley-based beers tested contained these proteins, with concentrations typically ranging from 19 to 45 parts per million, though some varieties measured as high as 130 ppm. For context, foods labeled “gluten-free” in most countries must contain fewer than 20 ppm.
Beers marketed as “gluten-reduced” use enzymes to break down gluten proteins, but fragments may remain. Truly gluten-free beers skip barley entirely, using grains like millet, sorghum, buckwheat, rice, or quinoa. Millet is the most common barley substitute because it behaves similarly during brewing, though its smaller, rounder kernels make the process more challenging. Buckwheat adds body and mouthfeel, while quinoa has been found to improve head retention and foam stability.
What Barley Adds Beyond Alcohol
Barley doesn’t just provide sugar for fermentation. It carries B vitamins (including thiamine, riboflavin, niacin, B6, and folic acid), minerals like potassium, phosphorus, magnesium, and iron, and polyphenols with antioxidant properties. Not all of these survive the brewing process intact, but enough transfer into the finished beer to give it a modest nutritional profile beyond just calories and alcohol.
The leftover barley after brewing, called spent grain, retains high levels of protein and fiber since the sugars have been extracted but the structural components remain. Most of it goes to cattle feed, though food producers have started incorporating it into products like high-fiber pasta. A single brewery can produce thousands of pounds of spent grain per week, making it one of the largest byproducts in the food industry.