Cask vs Keg: What’s the Difference?

Cask vs Keg beer… what’s the difference? They’re both beer. They’re both served in pubs. So aren’t they both just beer in barrels?

Not quite. Cask ale and keg beer may look similar behind the bar, but the way they’re brewed, stored, and served is different, and those differences make subtle (sometimes significant!) changes to how your pint tastes and feels. 

Over at Fonthill Brewing Co., Paul (our head brewer) has been busy crafting a very tasty kegged version of our very popular pale ale, Good Morning Captain, so we figured this was the perfect moment to provide you with some real, brewer-backed answers.

Cask vs Keg: What is the difference?

Cask beer (or “real ale”) has been around for centuries. Beer was traditionally brewed, fermented, and then conditioned in wooden (typically oak) casks. Though modern casks are stainless steel or aluminium, the principle remains the same: the beer continues to mature in a vented vessel until it’s served.

Keg beer is a more modern invention. Pressurised, airtight kegs became popular in the 20th century, which meant beers could stay fresher for longer, and therefore get transported over larger distances. It also provided a product that’s consistent in taste, hence, the rise of the popularity of lagers and international beer brands. 

So, without further ado, let’s dig in a little deeper into the differences between both vessels, and they type of beer they create.

Enjoy this topic? You may like our post on ale vs lager.

What Is a Cask?

A cask is a large wooden or metal, barrel-shaped vessel (with bulging sides), used to store and serve beer. Casks are traditionally laid on their side in a cellar, where the beer inside undergoes a “secondary fermentation”, meaning they develop gentle carbonation, flavour, and character while resting in the pub cellar, until it’s ready to be served. 

Casks have a circular hole (shive hole) on the curved side near the top. This is where a spile (a venting peg) is inserted into the cask to let carbon dioxide (produced during fermentation) gently escape. 

A Brief History of Cask

In Anglo-Saxon Britain, skilled coopers crafted casks from oak — and sometimes yew or pine — to store ale, honey, mead, and other products. By the Middle Ages, wooden casks became the one of the most important storage and transport containers used across all of Europe. By the 15th century, coopers took on an esteemed role. To become a cooper in London, your work would have been examined by the Mayor and Aldermen.

The transition to metal casks began in the mid-20th century. Aluminium casks first appeared in the 1940s, with Guinness introducing them in 1946. They quickly gained popularity;  by 1963, the last of Guinness’s own coopers were still working on wooden casks, but the shift was nearly complete. By the 1980s, wooden casks had largely disappeared from commercial use.

It’s no wonder then that in 1963, the Society for the Preservation of Beers from the Wood (SPBW) was founded over in Epsom. Their mission was to draw attention to their plight: that the new “‘sealed dustbins’ were threatening the availability of traditional draught beer.“

What Is Cask Beer?

Cask beer (also known as “real ale”) is beer that undergoes natural secondary fermentation in the cask itself. This creates soft carbonation, a slightly warmer serving temperature than keg beer, and complex flavours that evolve as the beer “breathes.”

Cask is associated with traditional styles like bitters, milds, and pale ales, and it’s loved and cherished for its heritage, character, and also the subtle differences from one cask to another.

What Is a Keg?

A keg is a pressurised container designed to hold beer (and other carbonated drinks) under airtight conditions. Made from stainless steel, kegs are tall and cylindrical, and built with thick walls to withstand internal pressure; they’re usually stored upright. Unlike casks, kegs are sealed, which keeps the beer fresher for longer. They’re dispensed with added gas — typically carbon dioxide and nitrogen mix — which maintains carbonation and pushes the beer to the tap. 

Different carbon dioxide and nitrogen ratios effect the mouthfeel of keg beers. Higher nitrogen levels create a smoother, creamier mouthfeel, as with Guinness. On the other hand, carbon dioxide produces bubbles which are sharper and more effervescent, giving the harder, fizzier mouthfeel (like most typical lagers).

How many pints are in a keg? Read our post to find out!

A Brief History of Keg

The first “keg beer” in the UK was launched in 1931 by Watney’s Brewery, London, with Watney’s Red Barrel. This was beer stored in pressurised metal containers and served with added carbon dioxide. It was marketed as consistent, clean, and longer-lasting than traditional cask ale. 

Breweries like Guinness soon switched to aluminium kegs (Guinness started in 1946), so they could suddenly export beer further afield without it spoiling.

By the 1960s and 1970s, kegs were rolling out of the breweries and into cellars everywhere across the country. They suited the growth of lager, which needed to be served cold and fizzy — something traditional cask systems couldn’t easily deliver.

Not all traditional ale drinkers were happy though. They wanted to defend cask against what they saw as “bland, fizzy keg.” This lead to the founding of CAMRA (Campaign for Real Ale) in 1971 — an organisation which, to this day, champions traditional cask ale.

What Is Keg Beer?

Keg beer is beer stored in a pressurised keg and served under gas pressure. This method means brewers can experiment with different levels of gas mixtures to create different mouthfeels. Aside from consistent carbonation, it also results in a longer shelf life, and crisp, sharp flavours. 

Keg beer is typically served colder than cask beer and suits modern styles like lagers, stouts, and IPAs. 

Anatomy of The Vessels: Cask vs Keg

The container plays a big role in how the beer inside behaves:

Casks

• Shape: Bulging sides with flat ends, designed to be laid on their side.
• Material: Traditionally wood, now usually stainless steel or aluminium.
• Vents: Casks are vented, which means they allow natural carbonation to escape during serving.
• Conditioning: The beer goes through secondary fermentation in the cask itself.

Kegs

• Shape: Tall and cylindrical, designed to be stood upright.
• Material: Stainless steel, with thicker walls to withstand pressure.
• Sealed: Airtight, meaning no oxygen gets in and the beer stays fresher for longer.
• Serving: Dispensed with added gas (usually CO₂ or CO₂/nitrogen mix) to push the beer out and maintain carbonation.

How They’re Served

Cask beer is usually hand-pulled from the cellar using a beer engine (or sometimes poured directly by gravity at events and festivals). No artificial gas is used — it’s all natural conditioning.

Keg beer is served under pressure, pushed through lines with gas, which keeps it fizzy and cold right until it pours into the glass.  

Shelf Life & Storage:

How Long Do Keg and Cask Last?

Cask: Once tapped, a cask only lasts around 3 to 5 days before it loses condition. This is why cask ale is often seen as a “living product” — it’s changing day by day, and timing matters.

Keg: A keg can last several weeks after being tapped, thanks to the sealed system and pressurisation.

Cask vs Keg: Differences in Taste & Texture

Cask beer

• Softer, smoother carbonation
• Slightly warmer (usually served around 11–13C)
• Complex flavours that can evolve as the beer “breathes”
• Often associated with traditional bitters, milds, and pale ales

Keg beer

• Colder and fizzier (served around 5–8C)
• Crisp, consistent taste
• Suits hop-forward IPAs, lagers, stouts, and sour beers
• Popular with modern craft breweries for bold flavour expression

Which Is Better, Cask or Keg?

It’s not about better or worse! Like all beer, it’s about just about style and preference.

Cask is perfect if you want a pint with heritage, subtlety, and character that changes from first pour to last.

Keg shines when you want consistency, bold flavours, a bit more fizz, or when the beer has to travel long distances without losing quality.

At The George, we believe the best pubs celebrate both — and so we do!

FAQs About Cask vs Keg

Your next order?

Now you know your casks from your kegs, you’ll understand why one pint feels smooth and mellow while another is cold, sharp, and fizzy. Both have their place, and the best way to find out what you prefer?

Try them side by side, of course! Check out our range of hand-crafted real cask ale and kegged beer, made right here in the heart of Tunbridge Wells.

Join us at our pub in Tunbridge Wells to taste the difference yourself. From traditional cask ales to crisp keg beers, we’ve got a fantastic range of craft beers and international brands waiting for you to try!