When most people think of stout, they think of Guinness, and when they think of porter, they think of… either, well, nothing or any number of beers, because they’re isn’t a beer as singular to porters as Guinness is to stout. I still think of Ska’s Ten Pin (R.I.P.) or Santa Fe Brewing’s State Pen Porter, but there isn’t a national or international brand that is associated with the style. Why is that? And what’s the difference between the two anyway?
To start, let’s talk about the difference in modern styles: There isn’t one. There is no difference between porters and stouts in modern beer. In the guidelines for judging the two beers, the only difference is the word “coffee” or “coffee-like” when talking about the roastiness of the stout, the idea being that porters are slightly less toasted. Both are going to be dark, possibly opaque, medium- to full-bodied, with a thick sturdy head and roasted malt character.
What this usually translates into for a brewer is roasted barley as opposed to roasted malted barley or dark malts. The use of unmalted roasted barley gives the beer more of a burnt, coffee-like aroma and flavor, as well as imparting more color for its weight compared to dark malts.
Unmalted, roasted barley also has a tie to history. During different times in history, whether to maintain strong tax revenue on malted barley or to control the end product, using unmalted barley was illegal in England. When the ban was lifted, it was used in porters made with higher alcohol content using mostly pale malts. Using more pale malt and smaller portions of roasted barley and dark malts allowed for greater efficiency (this greater efficiency also helped porter become one of the first beers with worldwide appeal, as England shipped porters all over the world). These stronger alcohol, more roasty beers were given the name, stout porters. So even historically, there wasn’t a difference. Stouts were just strong porters.
So, historically, the only difference is the stout will have higher alcohol content, and slightly more roasty aroma and flavor. But Guinness Draught’s ABV is 4.1-4.3 percent. How is that a “stout”? Well, that’s marketing. Porters have so fallen out of fashion that stout as a style has stepped on porter’s turf. It’s very similar to the distinction between a pale ale and session IPA (I’ll probably get in more shit for this claim than the port = stout claim, but pour a Sierra Nevada Pale Ale and tell me a session IPA has more hops). Enough people believed in the distinction enough that it became ingrained into our brains as a difference.
Robert Alan Wendeborn is a former cellar operator at Ska Brewing and current lead cellar operator at Tin Roof Brewing in Baton Rouge, Louisiana.