An imperial stout earns its higher price through more than the word imperial on the label. It takes far more malt, sits on the yeast for longer, is often matured for months, and because it is so heavy and so oxidisable, the difference between one that was handled well and one that was not shows up in every glass. What you are paying for, underneath the marketing, is density in the mouth, a long finish, and a beer that has not picked up the cardboard and dried fruit notes that come from too much oxygen. Get those three right and the price makes sense, get them wrong and a strong stout is a flat, bready, faintly fizzy drink that nobody should pay extra for.
Where The Strength And The Weight Come From
Imperial stout is a very high gravity dark ale. Where a normal stout sits somewhere in the five to six percent range, an imperial stout is usually somewhere in the ten to twelve percent range, and reaching that strength is a matter of loading the mash with enough fermentable sugar to sustain a long, strong fermentation. A brewery that wants twelve percent alcohol cannot get there with a single normal mash, so it either steps up the gravity, or it uses a technique such as incremental hopping, where a strong wort is diluted down and re-fermented, or it simply runs a much richer wort through the same vessel. The result is a beer with a lot more dissolved extract still in it, and that is the source of the weight people describe as dense or thick.
The official judging body, which publishes the BJCP style guidelines, puts imperial stout at ten to twelve percent alcohol by volume, which tells you how narrow the window is. Anything lighter and you are drinking a strong stout, anything heavier and the alcohol starts to be the loudest thing in the glass. This is worth holding onto, because the alcohol in a well made imperial stout should sit behind the malt rather than in front of it. When you can taste the heat more than the roast, the beer has usually been left in the wrong shape for too long rather than brewed too strong.
There is a related cost people do not think about, which is time. A big, cold-fermented stout that also wants to express oak or barrel character cannot be rushed, and a brewery that sells one of these cheaply has almost always cut something out of the process, whether that is maturation time, the amount of malt, or the care taken in packaging. The older articles on this blog about barrel aging and the effect of oak on a finished beer cover that side in more detail, and the price of those barrels is real money that ends up in the bottle.
Oxidation Is The Fault That Cannot Be Fixed
The single biggest reason a strong dark beer disappoints is oxidation, and it is a one way street. When a dark, heavily roasted, high gravity beer takes on oxygen, a chain of chemical reactions turns the black liquid browner and produces the flavours of wet cardboard, bruised apple, dry sherry and old leather. It is a distinctive signature, and once it is there it will never come out. No amount of extra ageing will improve a beer that has already gone this way, and no amount of cold storage will hide it either.
This is why a dark beer is more fragile than a pale one, and why packaging matters so much. Roasted malt contains a lot of the reactive compounds that fuel these reactions, so a strong stout has both the chemistry and the time to go wrong. Oxygen gets in at transfer, at the tank, and through the closure, and once the beer is in a bottle or can, the only thing standing between it and ruin is how much headspace there is and whether the packaging excludes light and air. An imperial stout that has been through warm transport in a truck that sat in the sun is a beer that has already lost the argument, and no one at the bar is going to know.
There is a useful habit that helps you read all of this without any technical knowledge. Put the glass down halfway through and come back to it twenty minutes later. A healthy imperial stout will still be opaque black and will have pulled in slightly as it cools. A tired one will be a shade lighter, a shade browner, and the aroma that has developed will smell like a cupboard rather than a brewery.
How The Format Changes What You Are Paying For
Imperial stouts are among the beers where the packaging is doing more work than usual, and it changes both how the beer arrives and how it should be poured. A brewery is far more likely to put a beer this fragile in a bottle or a can than on draft, because draft means open exposure to oxygen every single time you pour it, and a beer this oxidisable punishes that far harder than a pale ale would. A nitro imperial stout is the exception, and it comes with its own instructions, which we will come to.
| Format | What it does for the beer | What to watch |
|---|---|---|
| Bottle, 500 mL | Large format, low oxygen to headspace ratio, good for ageing beer | Warm storage ruins it, so check for a dark bottle |
| Can, 355 mL | Light tight and cheap to ship, small single serving | Sold warm, so buy it cold and drink it cold |
| Nitro bottle | Nitrogen gives a thick, cascading, creamy head with almost no bite | Pour carefully down the side, never straight down, or the head collapses |
| Draft | Freshest possible pour, and the only format served at cellar temperature | The most exposed to oxygen, so drink it in one sitting |
The nitro pour is the one most people get wrong. A nitro stout is cold and smooth, and it deserves a wide glass, but the pour has to be gentle and down the side of the glass rather than onto the head, and it takes a moment to settle. Pour it straight in from height and you flatten the cascade that the nitrogen is trying to build, which throws away the entire reason a brewery put the beer under nitrogen in the first place. Our piece on bottle conditioning covers how the gas itself behaves.
How To Judge One Before You Buy It
- Check the alcohol by volume against the ten to twelve percent window, because a beer labelled imperial that sits at eight percent is a strong stout and you should pay a strong stout price.
- Look for a best before date and a fill date if one is printed, since age in this category is the difference between a treat and a lesson.
- Buy cold. A strong dark beer that has spent an afternoon in a warm car is already oxidising whether or not you know it.
- Ask the seller whether it is nitro, and if so whether it has been upright and cold, because a nitro keg that has been shaken will pour flat.
- Pour into a tulip or a snifter rather than a mug, since a wide open glass gives a big dark beer nowhere to collect its aroma.
- Drink it fresh if it is young, and let an aged one stand in the glass, because a barrel aged imperial stout that is meant to be opened and savoured is a different proposition from a fresh one.
What You Should Expect To Pay For
The honest answer is that an imperial stout should cost meaningfully more than a standard stout, because it contains more of everything and has taken longer to make, and the base cost of a bottle of stout already has barley, malt, hops, yeast and a fermenter in it. What you should not accept is a very high price attached to a beer that is thin, light coloured and sour smelling, because none of that is a style choice. Those are faults, and paying extra for a fault is how people decide the whole category is overpriced.
There is one more health point worth making plainly, since strong beer gets talked about loosely. Beer made from barley contains gluten, and no amount of ageing or strength changes that, so a milk stout or an imperial stout is not something a person with coeliac disease can drink. The alcohol content is the other half of it, and a twelve percent beer carries its effects faster and lasts longer than a four percent one for the same volume, which is the plain reason these beers are poured in smaller measures or shared. Nothing about a dark roast malt makes a beer healthier, and it is worth saying because the word stout still carries a faintly wholesome image that the liquid does not support.
Where To Start If You Have Never Had One
If your experience of strong dark beer is a sweet coffee flavoured porter bought warm in a pub, you are starting from a bad sample rather than a bad style. Start instead with a bottle that has been kept cold, pour it into a tulip glass, and give it a smell before you taste anything, since the aroma is where the roast and the barrel and any oxidation all announce themselves. Drink it slowly and warm, because an imperial stout that has warmed to cellar temperature tastes of a completely different set of compounds than the same beer cold, and a good one opens up as it does. If what you smell is roast, coffee, chocolate and dark fruit rather than cardboard and vinegar, you have found the thing that justifies the price, and you will recognize it in every bottle after this one. Our earlier piece on creamy stouts covers the lighter and sweeter end of the same family, and is a gentler place to start if the strength is not for you today.
