A common assumption about alcohol content in beer is related to beers darker brown in color and usually of a thicker consistency, such as Guinness or porters. Many people think that the darker a beer is, the “stronger” it is. A darker beer, they think, has more alcohol than a light-colored beer. Nothing could be further from the truth. The color of dark beers has nothing to do with their alcohol content. Instead, is is the darker malts that are used, which have been roasted longer, that give the dark colors and the more “malty” flavor. Many dark beers are of the lowest alcohol percentage, while a very pale beer may be the highest.
Look at the aforementioned Guinness. This Irish mainstay is the darkest beer most casual beer drinkers know, and in a typical bar, it is probably the darkest beer on draft, or even on inventory. As well, it probably is among the lowest alcohol beers. Regular Guinness Draught, at around 4.2% alcohol by volume, has about the same punch as a Bud Light. They do make stronger versions.
This is not to say that dark beers should be assumed to be light on alcohol! While dark beers are not automatically the strongest beers, many can pack a punch. For example, Bocks can be light or dark, but both tend to come in at over 6% alcohol-by-volume. Many assume the word ‘Bock’ refers to any and all dark beers, but its really a German word for strong beer (derived from Einbeck). Then, of course, there are Doppelbocks, which are even stronger.
There are other dark beer styles are associated with fairly high alcohol content, as well. Stouts tend to be 7 or 8% alcohol-by-volume and Imperial or Russian Stouts are even higher than 9% alcohol.
Notes on the words Strong and Light in Beer
Some beer drinkers might consider strong to reflect the taste of a beer. Therefore, any beer with bold strong flavors may qualify, even if the beer is low in alcohol but high in hops, for example. But for beer brewers, the strength of a beer is related to its alcohol content, which can be determined by measuring its specific gravity or by measuring the percentage of alcohol directly. What beers are considered strong, however, depends on the country. In America, we consider an ‘American Strong Ale’ to be an ale with an alcohol content of higher than 7%, whereas in England, a strong ale is an ale with higher than 5% alcohol.
The opposite of a strong beer is not “mild beer.” The term mild in beer usually relates to flavor, and specifically to hops content. So a mild beer will be a beer with less hops, and therefore less bitter flavors.
On the other hand, the term ‘light beer’ doesn’t help much, either. The meaning of the word light applied to beer is not consistent. Just as with the word strong, the meaning of light and low-alcohol varies from country to country.
In Australia, beer is considered light if it has between 2.2 and 3.2% ABV (alcohol by-volume). And, in Canada, beer is light if it has between 2.6 and 4% ABV.
The United States muddies the water a bit. Beer in the U.S. is light if it has around 4% ABV. However, the term light is usually related to calories. Beer is light if it has around 20 to 33% fewer calories than regular beer. It is possible to have a low-alcohol beer that is not lower in calories. If you see the term ‘low-alcohol’ applied to a beer, this should not be assumed to be a low calorie beer. Consistent to the information already presented here, low-alcohol beers do not tend to do well in the United States! In the early 1980’s, Anheuser-Busch introduced a low-alcohol beer (LA) that pretty-much flunked. Yet, light beer, in America, has the strongest market share.
You might also be interested in reading about how Miller tried to sue other beer companies for using the word light in their beers.