We’re sure you’ve heard it before: All beer is either an ale or a lager. But is that true? And what actually is the difference between lagers and ales? We sat down with Sam Tierney, Brewery Manager of our Propagator R&D Brewhouse, to get to the bottom of it.

“An ale says ‘ale’ on the label and a lager says ‘lager’ on the label,” he told us, laughing. All jokes aside, read along as we dive into the differences between ales and lagers – everything from the basics to the nitty-gritty microbiology of it all.

Lager Yeast vs. Ale Yeast

The simplest explanation for the difference between lagers and ales is that they use different yeasts during fermentation. Lagers are made with lager yeast and ales are made with ale yeast. There are some exceptions to this generality that Sam likes to think of as “hybrids” (more on that later).

While reading about ales and lagers, you might see a lot of information about top-fermenting and bottom-fermenting yeast. “Before the science of genetics and microbiology was well understood, ‘top’ and ‘bottom’ fermentation descriptions were used to differentiate yeast types based on how they looked during fermentation,” Sam explained.

“Top-fermentation was done with yeasts that produced large, foamy heads that could be seen in open-top fermentation tanks used before the modern era,” he said. The yeasts that didn’t produce the large, foamy heads were considered bottom-fermenting. “We now know that these yeasts are almost always divided into two different species. The ‘bottom-fermenting’ yeasts are Saccharomyces pastorianus, commonly called lager yeast, and the ‘top-fermenting’ yeasts are Saccharomyces cerevisiae, commonly called ale yeast.”

Installation of six 1,500-barrel fermentation tanks at our Paso Robles brewery in October 2021

Of course, there are a few exceptions. For example, “some classic ‘lager’ yeasts are genetically ‘ale’ yeasts that have developed special adaptations making them phenotypically present just like lager yeasts in the brewery,” Sam told us. Thankfully (for the sake of our own understanding), many brewers tend to focus on the way yeast behaves – rather than their genetic profile – in order to classify them.

“But on the flip side, many breweries over the years have chosen to use either lager or ale yeast for all their beers and simply call some lagers and some ales,” Sam explained, referring back to his opening joke about the main difference being the labels.

Cold Temperatures vs. Warm Temperatures

Fermentation temperature also plays a factor in the difference between lagers and ales. Generally, the two species of yeast have genetic differences that allow them to thrive best at different temperatures.

Ale yeasts tend to ferment at warmer temperatures, generally in the 60°F to 75°F range, but sometimes going as high as 100°F. These warmer temperatures also increase the rate of fermentation and the production of carbon dioxide, which contribute to the yeast rising to the top of the beer during fermentation.

Lager yeasts, on the other hand, tend to ferment at colder temperatures, typically around 45°F to 55°F. The colder temperature slows down the fermentation process and produces less foaming.

Of course, as it seems with everything related to the lagers versus ales distinction, it’s not always so cut-and-dry. “While those are the general guidelines,” Sam told us, “there are some lager yeast strains that are happy fermenting at warmer temperatures, and some ale yeasts that can ferment just fine at lager temperatures.”

Here they are again – the hybrids. The California Common and Cold IPA are two examples of beer styles that are made with lager yeast and fermented at warmer, ‘ale’ temperatures. On the other end of the spectrum is the Kolsch, which is made with an ale yeast that is ‘comfortable’ fermenting down to the warmer end of lager temperatures.

Taste Differences Between Lagers and Ales

Some ales and lagers can be distinguished by their flavor. Colder temperatures often cause yeast to produce fewer aromatic compounds during fermentation than warmer temperatures. This means that lagers generally have a ‘cleaner’ taste that allows the malt and hops to be more noticeable. Ales, on the other hand, tend to have strong fruity and spicy flavors that balance out the malt and hops.

If you focus on the fruity and spicy character as the hallmark of an ale, you can start to notice the difference in most beer.

— Sam Tierney, Brewery Manager

Consider two iconic Firestone beers as an example – Pivo Pilsner and Mind Haze IPA. Pilsners fall under the ‘lager category,’ and Pivo is a great example of a crisp, clean-tasting beer that allows the malt and hops to shine through. Mind Haze, on the other hand, is a juicy beer with fruity flavors that were achieved both through the yeast and fermentation and through its featured hops.

Another, perhaps more obvious, example is 805 Beer versus 805 Cerveza. 805 is an ale, while Cerveza is a lager. “If you taste the two side-by-side, you will notice a fruity character in 805 Beer that many people find evocative of banana candy or juicy fruit gum,” Sam said. “In contrast, 805 Cerveza does not have this flavor, and this allows the lime addition and clean malty character to take center stage.”

But again, it’s not always so simple. Sam explained: “Even so, some ales are relatively clean in profile and can seem lager-like. In general, lager and ale styles have other differentiating aspects beyond just the type of yeast used, making it useful to know your beer styles. The examples of hybrid styles show that changing yeast or fermentation doesn’t always make for a very different beer.”


Hybrid styles and breweries’ own discretion in labeling their beers can complicate it a bit, but here’s a recap of the basics: most beers are either lagers or ales, and the primary distinction is that they’re made with different species of yeast. Ale yeast tends to ferment better at warmer temperatures, and lager yeast at cooler temperatures. Generally, you can taste the difference between lagers and ales by zeroing in on fruity or spicy characteristics.

Have questions about lagers and ales, or anything else beer related? Send us a message on Instagram or Facebook, and we’ll look into it for you.