A few years ago, if I were a game show contestant and asked the difference between an ale and a lager, I couldn’t have told you, not even for a million dollars. I simply didn’t know and didn’t know that I needed to care. But as my drinking palate expanded and my vocabulary grew, I knew I should probably get to the bottom of this very fundamental question.

Almost all beer (with the exception of a few crazy ones) falls under the category of being an ale or a lager. Like most of the organisms on the planet can be divided into Animal or Vegetable, lagers and ales are super-categories for beer. (If you’re interested in the pedigree, The Fermentarium has a great chart of all the beer styles)

But what’s the difference between the two? The stock answer, repeated with a memorized monotony by brewery tour guides, is that ales are top fermented and lagers are bottom fermented. Which, to anyone but a beer geek, means absolutely nothing.

Luckily, I went on a brewery tour at the Stone Brewery in Escondido California and I was fortunate enough to have a brewer set me straight. He was an excellent guide, with a bit of humor and a lot of science. He got as geeky and technical as you’d ask him to, while still being able to explain things in a clear way even to a novice.

I learned the real meaning behind the two basic beer terms, and I hope that this is the last explanation of the difference that you’ll ever have to read.

When beer is brewed, there’s a lot going on. But the one thing that makes beer special is that it’s made by animals little molecules of yeast. When yeast is added to the sugars and grain mixture (called the wort), the yeast cells devour them and produce waste in the form of alcohol and carbon dioxide.

It is the same process metabolically as what happens in our muscles sugars get converted to other molecules as they get used up only in our muscles the byproduct is lactic acid, the stuff that makes it hurt to run too hard. Can you imagine if our muscles produced alcohol as a byproduct instead? You’d get drunk after running a few miles

Anyway, when the yeast is doing its job munching away at sugar molecules and burping CO2 and alcoholic goodness, the yeast cells grow, reproduce and generally have a party. As the process continues, they begin to clump together or “flocculate.”

So, the tiny yeast particles stick together in a similar way that fat, fluffy snowflakes form, by grabbing onto one another. In fact, flocculated yeast looks a lot like the snow in a snow globe, if that snow globe were filled with beer.

So what does it matter that the yeast clumps? There are many different types of yeast, and they each have different habits, growth rates, alcohol tolerances that are the result of our artificial breeding for brewing. The head brewer of Sam Adams is said to have developed a strain of yeast that could survive high alcohol content called “ninja yeast.”

In general, though, there are two major types of yeast. And depending on which you have, the yeast will either clump and go to the bottom of the fermenter, or rise to the top. This is where the term “top fermenting” and “bottom fermenting” comes from.

Lager yeast clumps at the bottom and prefer to be brewed cold. And, most American domestic beer falls under the lager category. It is a win-win situation for macro brewers to use lager yeast and choose lager beers because they are very efficient (more so than ale yeast) in getting at all the sugar in the fermenter. This results in a crisper, cleaner taste than an ale, in which there are more sugars and other flavors leftover.

A cold lager makes its flavor better and tighter, a warm lager is not fun to drink because there isn’t any sweetness left behind, just bitterness. It is for this reason that we get ads professing how truly cold a beer like Coors is.

The inverse is true for ales, though, who are brewed and stored at higher temperatures, and are a bit less efficient at taking out all the sugar. Let an ale warm up, and a whole other depth of flavors come out.

So what does this mean to you? If you’re at a restaurant and you order an ale, tell them to skip the cold glass and tell them why. Bonus points if you say “flocculate” to your server.


  1. Ale vs Lager – Difference and Comparison | Diffen
  2. 3 Tips for Digestive Problems
  3. Lager Beer vs. Ale Beer—Does It Matter? – About Beer Magazine

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