How to Brew High Gravity Beers

Written by Josh Charig

23 January 2023

There’s a stage I think every homebrewer goes through, they brew a few pale ales and once they get the hang of it, a lightbulb goes on: they can brew a strong beer. They can brew many strong beers for significantly cheaper than buying them. The beer world is their oyster, and it’s time to ride the high ABV wave.

It’s exciting because some of the best beers in the world are high ABV strong beers and we have the ability to recreate this at home. They tend to be expensive due to alcohol duty increasing with ABV, plus some of the finer high ABV beers are imported, such as all those fantastic Belgian beers and American triple IPAs.

Whilst the ingredients for a high gravity beer costs a bit more than a session strength one, it’s still a fraction of the cost compared to shop bought and it’s a great opportunity to develop brewing skills, opening up a range of styles possible to brew.

How Do I Increase Gravity For A Strong Beer?

To put it simply, gravity is the measure of dissolved sugar in a liquid. So what we’re really after is an increase in sugar. In beer, we get the sugar from malts, so increasing the amount of malt will mean more sugar. We can also add other sources of sugar such as honey, DME, dextrose or even sucrose (table sugar) in a pinch.

If you have a recipe for a session strength beer and you’d like to make it imperial strength, as a rule of thumb increase the base malt whilst keeping any adjunct malts the same. Some tweaking will be needed which differs recipe to recipe, but on the whole the extra sugars should come from the base malts.

Mash tuns are usually efficient at specific gravities for specific volumes. For example a Grainfather works most efficiently making roughly 23 litres of 1.040-1.050 wort. Trying to get gravities of 1.080 or higher becomes challenging. Adding more malt reduces efficiency so less sugars are obtained, meaning more malt needs to be added in a finite space which can’t hold that much malt. One way around this is to brew smaller batches, another is to do reiterated mashes.

A reiterated mash is when half the grain bill is mashed in, drained off, and then the remaining half is mashed into the existing wort. This helps increase efficiency and get around the space constraints.

Are all Sugars Equal?

Not quite. High amounts of malt will result in a beer with a heavy mouthfeel and as the beer ages, more intense malty flavours will come out. This isn’t a bad thing by any means and depends on the style of beer being made. A barleywine or imperial stout for example benefits from high amounts of malt. This can add a stewed dark fruit flavour depending on the malts used.

Belgian styles and imperial IPAs tend to be stronger in ABV whilst keeping the body relatively light. Whilst the malt content is increased, a lot of the heavy lifting is done with either dextrose or invert sugar. Both invert sugar and dextrose (or brewing sugar) are short chain sugars yeast can very easily metabolise, meaning it gets converted into alcohol easily without leaving anything behind for sweetness or body. This results in a stronger ABV beer which is more drinkable.

Sucrose can be used, but can dry out a beer too much making it astringent. This can be desirable in limited amounts in some styles but is generally avoided. I’ve found that using 500g in a 23-25L brew doesn’t seem to have any negative effects.

Do I Have to Change Other Ingredients?

With an increased malt character, other ingredients will be needed to balance this out. In a typical strong beer – like a barleywine, IIPA, imperial lager etc – this usually means an increase in bittering and flavour hops. This is where IBU measurements get a bit theoretical and maybe less helpful. Whilst there’s a correlation between increased IBU and increased bitterness, IBU is not an exact measurement of perceived bitterness. More hops are needed to balance the increased malt levels, in a way “cancelling” each other out.

For example, brewing a barleywine with a huge malt bill will taste very rich, thick and sweet beyond cloying without a decent bittering addition balancing that out. On paper, with a good amount of hops, the IBUs might be really high, but it will actually have a pretty balanced flavour as the increased bitterness will counter than increased sweetness.

A better indication of hop bitterness to malt profile would be the BU:GU ratio, or bitterness units to gravity units. The higher the BU:GU ratio the more bitter the beer is. The lower the BU:GU the higher the sweetness. Imperial strength beers with session strength hopping will be cloyingly sweet and difficult to drink.

Like everything else, there are caveats. Balance doesn’t have to come from bittering or flavour hops. Belgian beers find balance in adding herbs and spices such as coriander and using expressive and flavourful yeasts. Which brings us onto our next section…

How Does Fermentation Change?

Fermentation is an important step to get right. With an increase in sugar we must increase the yeast’s cell count. With a gravity of 1.060 or greater, that’s usually “make a starter” or “two rehydrated dried yeast packs” territory. Using a regular pitch rate for a high gravity wort will stress the yeast out, throwing out loads of off flavours. It can also stall fermentation leaving a lot of unfermented sugars and not a terribly strong beer.

Things get a bit nuanced when it comes to temperature. For clean beers such as IIPAs or modern strong stouts, fermenting slightly cooler will get cleaner results. I’d normally ferment an IPA at 20°C, but for DIPAs I ferment around 18°C. Fermenting too warm can very easily throw out off flavours such as phenols and esters.

In Belgian beers we actually want those phenols and esters as they are stylistically desirable. They are quite definitive even! Whilst each specific strain has a sweet spot, fermenting in the low-mid 20s is quite common, with a temperature increase towards the end of fermentation to dry the beer out. There can still be off flavours produced though and it’s important to hold the fermentation at a stable temperature.

Generally speaking, the warmer the fermentation the more phenols and esters are produced. So if you want to limit these flavours ferment at the cooler end of the spectrum.

A really good type of yeast for high ABV beers is kveik yeast. It actually prefers higher gravity wort and performs better than in low gravity wort. It has some great and unique flavours and ferments ultra fast at high temps. Check out our guide to kveik for more information.

Depending how high gravity you want to go, you may need specialist yeast which can tolerate high ABV. Alcohol kills yeasts and bacteria, including brewers’ yeast saccharomyces cerevisiae, it’s just the vast majority of beers don’t get to alcohol levels which are lethal for it. Different strains have different tolerances, US-05 can handle up to 11% for example, so choosing a high alcohol tolerant strain is important. It’s also possible to co-pitch yeasts and some brewers use champagne yeast to dry out a beer.

Does High Gravity Mean High ABV?

There is a correlation between gravity and ABV but it doesn’t necessarily mean the higher the gravity the higher the ABV. As explained above, bad yeast health/count will result in the fermentation stopping early leaving a high finishing gravity. If the beer needs to be dry, use a suitable yeast with a high pitch rate and highly fermentable sugars (i.e. dextrose) to increase the alcohol levels.

Some styles benefit from increased sweetness, such as certain imperial stouts and Scotch ales, so a high FG is preferred.

Does the Beer Need to Condition?

This comes down to individual styles. High ABV IPAs should still be drunk fresh as hop flavour and aroma dissipate quickly, but malt and some yeast forward styles do benefit from conditioning. It gives time for some of the harsher flavours to mellow out and brings forward those intense malty characteristics described above. Time is a great healer for homebrew and most strong styles do benefit from some conditioning.

Malt forward beers like imperial stout, lagers and barleywines will benefit from extended conditioning times and can be left up to six months to a year! It’s quite common as well to age with wood – whether in a barrel, on woodchips or oak spirals etc. – for added dimension.

By the time it comes to serving you should have a complex beer made to be sipped and savoured. Let us know how your stronger beers came out!

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