The tangled web of dark beers

Paul Crowther unravels the history and stylistic nuances of stout and porter


I work in a tiny bottle shop called the Yardhouse in Tynemouth. Part of what I love about my job is interacting with customers, talking to them about different beer styles and getting them excited about beer. One question I get fairly often is “what is the difference between stouts and porters?” and my stock response is to shrug my shoulders and advise “Not much really.”

You might think this answer somewhat flippant and flying in the face of beer experts with decades more experience, education and qualifications than me. Surely if these two styles exist, there is a defined and understood technical difference, right? Well let’s consult Randy Mosher, author of numerous books including the seminal work Tasting Beer in which he asks:

“Think you know what a porter is?” 

No Randy, I absolutely don’t, there lots of conflicting evidence, historical and geographical interpretations, I don’t know what a porter is Randy.

“Me neither.” Randy goes on to admit.


So if industry experts don’t really know what a porter is, how can we mere mortals hope to pin down a definition, let alone begin to compare it to stout?

The style has evolved throughout history, and has evolved alongside stout. In the same way that we have English, West Coast and New England IPAs, there are different variants of porters and stouts that have risen and fallen over time, but unlike IPAs have never really had agreed names attached to them.

1722-1800 - Brown malt porter 

In the 18th century, the majority of malt used in beer was brown malt. Brown malt differed from more modern pale malt by being dried in wood-fired kilns. Wood burns at a much lower temperature than the coke used for pale malt, meaning the kilning process took longer, giving a markedly darker colour and destroying more of the enzymes that break carbohydrates down into simple sugars during the brewing process.

Early porters were made exclusively with this brown malt. The first porter is often attributed to Ralph Harwood of Bell Brewing in Shoreditch, but some beer historians argue that multiple brewers simultaneously started brewing this style of the beer in early 18th century England, and that it evolved naturally from brown ale. 

Porters were a response to customer demand. At the time, the two types of ale available were younger mild beers and aged, stale beers; it was popular at the time for patrons to mix and match stale and mild in various quantities to create their own perfect beer cocktail. Porter effectively replicated this character in a single ale, in a single barrel and was highly popular with drinkers and with publicans who no longer had to mess around with blending different beers.

These early porters would bear little relation to modern day interpretations. They’d be a much lighter brown, very viscous due to brown malt having that lower enzyme level, and lacking any of the chocolate, coffee and caramel flavours you might associate with the style today. 

Although references to ‘stout beer’ pre date porter, these early references are just referring to strong beer in the literal definition of ‘stout’. It wasn’t long before the term stout was attached to porter and by the 1750s there were references to ‘stout porters’, a descriptor to signify that this porter was of a higher strength. These early stouts would similarly have had a brown colour and lack any of the roast character you would expect of a modern day stout, as it was still made with 100% brown malt.

1800-1850 - Pale malt porter

Around 1800, the first real divergence occurs for porter. Measuring beer ABV became easier through the invention of the hydrometer. Through this, brewers realised that pale malt was a lot more efficient for creating alcohol, because it was kilned faster (with coke instead of wood), had more enzymes and could convert more of its starch to fermentable sugars. This made pale malt a lot more commercially attractive for brewers.

However, as its name would suggest, pale malt is paler than brown malt and beers made solely with pale malt were unsurprisingly lighter in colour. However, brewers still needed to get the brown colour of a porter and stout porter, so would only use around 30-50% pale malt, with the rest of the bill made up of brown or amber malt (kilned longer than brown malt to produce a darker colour).

This beer would have been less viscous and bready, and a more refreshing drink all over. It would still have lacked the coffee and chocolate aromas we expect of a porter today, much more akin to a modern brown ale than anything else.

There is some evidence at this point that stout porter diverged somewhat from porter, in that it did not employ amber malt at all, but instead was a 50/50 blend of pale and brown malt. This would give it a drier body but likely a lighter colour.

1850-1974 - Roasted malt stout/porter

In the early 19th century, the process for making roasted malts was developed. Roasted malts are fired in a drum until they are very dark brown and almost black. This produces a malt that can darken beer with only a small amount and imparts the chocolate, coffee and roasted flavours.

This is really where stouts and porters began to take on the form we know today. They utilised around 90% pale malt, making them much more efficient to brew and the remaining 10% was roasted, amber and brown malt. 

At this point, porter and stout became synonymous with each other; although stout was generally considered a ‘strong porter’ there were no other identifiable differences between the styles.

Over time however, brewers preferred simply to use the label stout, which became more recognisable for the drinker, while ‘porter’ faded into disuse. By the 1950s, writer John DeClerck was describing porter as ‘light gravity stout’ rather than stout being a high gravity porter.

By 1974, even Guinness had dropped the name porter from its range, and no porters at all were being brewed in the UK. Stout had consumed its older brother whole and come out victorious. Lower strength dark beers were by this point just being called stouts.

1990s - Today’s modern porter

Porter may have died in Britain, but the craft beer boom was about to re-animate it. Breweries such as Sierra Nevada and Great Lakes Brewing company made their own interpretations of porters, and brewers in the UK eventually began following the trend.

Porter may have died in Britain, but the craft beer boom was about to re-animate it

In 1995, the Beer Judge Certification Programme (BCJP) became independent of the American Homebrewers Association (AHA). Around this time, it began to develop style guidelines against which it could judge beers. From its first guides, it split porter into two styles: ‘robust’ and ‘brown’ which in later guides changed to ‘American’ and ‘English’ porter respectively.

The 1997 BJCP guideline describes Robust Porter as:

“A dark ale with a fairly full body, a coffee-like dryness from the use of roasted malts (as opposed to the roast barley character of stouts). A malty flavor, and a strong hop character that balances these other factors. Dark brown to black color.”

This is the first time that anyone had described a contrasting flavour difference between stout and porter, directly comparing the two and implying a roasted barley character was inappropriate for porters. The BJCP, to be fair, was not looking at history, but describing the beer scene as it existed at the time. It described a snapshot of what porter was in the mid-nineties. 

On the question of strength too, the BJCP guidelines were not afraid to muddy the waters, giving the porter an ABV of 4-6%, and dry stout 3.7%-5.7%. This is because the stouts in the UK at the time included old style porters that had just dropped the name. In the current 2005 guidelines, American Porter is guided to be 4.8-6.5% with Irish Stout at 4-4.5%. In 2018, Brewlab in Sunderland published a report of over 1500 commercial beers it had analysed, and found that the average stout was 4.8% and the average porter was 5%. Porter is now officially more stout than stout.

The issue with this is that only some brewers are now following this modern porter definition, while others are sticking to the older definitions of what porter is. Some brewers are insistent that stouts should continue to be the stronger ABV and that roasted barley is absolutely fine to be included. There are sub styles of stout, such as sweet stout that may eschew roasted barley and look very similar to a modern porter. Some porters go back beyond the 1850s and emulate the older brown malt porters, eschewing the use of roasted malts entirely. 

For me, as long as porters and stouts represent such a broad range of beers, my answer to the question of “what’s the difference between a porter and a stout?” will continue to be “Not much really”.

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