The strength of a beer is simply the amount of alcohol in it, litre for litre. It’s measured in ABV (alcohol by volume), so a beer described as 4% ABV contains 40ml of alcohol per litre of beer. All alcoholic drinks use the same unit of measurement, and it can dramatically affect the flavour and mouthfeel of the beer.

Commercially available beer ranges in strength from alcohol-free to around 7% ABV. Generally, lagers, bitters and stouts are between 4% and 5%, with IPA between 5% and 7%. “Alcohol-free” beers can legally contain up to 0.5% alcohol in most countries.

Stout has an average strength of around 4% ABV. However, there’s always variation within the style, such as Imperial Stouts. These beers can exceed16% ABV, but often float around the 11% - 13% mark. In fact, the term ‘Imperial’, when placed before any beer style, will always mean it’s a stronger version of that style.

IPAs vary in strength and can differ in ABV depending on where in the world they are brewed. Typically, an IPA brewed in the US can reach up to 7% ABV while in the UK you’re more likely to see them lodged between 5% and 6.5% ABV. But in reality, there are no rules. So you can find IPA ranging from alcohol free to upwards of 11%.

The 'double' of the name actually refers to the amount of hops and malt used in the brewing process, which is typically around twice that of an IPA. Double (or Imperial) IPAs therefore also promise a higher ABV of around 8% - 9.5% (due to more sugars being eaten through fermentation).

BrewDog famously got into a rivalry with German brewer Schorschbräu to produce the strongest traditionally made beer, and came up with “Strength in Numbers” (57.8% ABV). Check out Tactical Nuclear Penguin and Sink the Bismarck for more epic high ABV beers!