The are thousands of homebrew recipes online, plus there are plenty of recipes right here on Home Brew Answers that I have published. The trouble is, with home brew recipes they don’t always fit with the way each of us brews.
Not everybody brews the same amount of beer, maybe their process is different such as BIAB (brew in a bag) brewers who have different efficiencies or maybe you brew extract beers, check out this guide here if need to convert recipes from all grain to extract or vice versa.
The thing is there is no universal home brew process so at some point you’ll want to adjust a recipe. How you go about doing that is what we are looking at in this article. Scaling a beer recipe isn’t that hard and once you know the basics, there will be no recipe you cannot brew.
The Easy Option
If you use brewing software then many of the popular choices have options to scale a recipe. Once you have found a recipe you like, input the ingredients and their amounts into the software according to that recipe’s specifications. It is then a case of finding the option to scale the recipe to the amount you want to brew or the efficiency.
If you use brewing software and it has this facility look no further. If you want to know how it works however then read on. Remember that knowing how something works means you can do things on the fly without relying on a computer and software.
Scaling by Volume
The vast majority of homebrew recipes you’ll find in books and online are formulated to make around 5 gallons of beer. In the UK this is just shy of 23 litres in the US just under 19 litres. If you are brewing the exact recipe that is fine continue on without a worry. If however you want to adjust the recipe for any particular reason to make a different amount of finished beer how do you go about it.
Scaling a home brew recipe is relatively simple. There are many reasons of course on why you may want to scale a recipe up or down. The most likely reason to brew a certain amount is down to the equipment you are using.
Probably the most common measure for a home brew recipe is 19 litres or 5 US gallons this is due to many home brewers preference towards kegging beer in Cornelius kegs which hold exactly 19 litres. In the UK most home brew equipment such as fermenting vessels and boilers are designed to hold 23 litres so a common homebrew recipe in the UK can be 23 litres or 5 imperial gallons. Some brewers, me included will look at recipes and adjust them to my equipment, ensuring there is enough headroom and capacity in the equipment I use.
Equipment is only one reason why you would adjust a recipe of course. You may want to brew a small batch of beer to test or experiment with ingredients or techniques you haven’t used before. Small batch brewing is becoming more and more popular with people just getting into brewing who don’t want to commit to making 40 pints of beer but rather just have a handful of bottles.
The opposite is also true for brewers who don’t have much time to devote to a whole brewday and therefore brew larger batches but less often. Scaling a recipe up means they got more beer for the same amount of time spent brewing.
How To Scale A Beer Recipe By Volume
Scaling a beer recipe by volume is easy. Take all of the ingredients in the recipe, this will include each type of grain, hop, yeast, spice, fruit or other flavourings listed. Divide by the volume listed for the recipe and then multiply by the volume you intend to brew. It’s that simple.
As an example If a 21 litre recipe calls for 3.5kg of Maris Otter and you intend to brew 15 litres simply do the following:
3.5 / 21 * 15 = 2.5 – so you would need 2.5kg of Maris Otter for the recipe.
You then work through each type of grain listed in the recipe to get the amounts used for each type and do exactly the same for each addition of hops as well as the amount of yeast to pitch and any other ingredients.
The same method is also used if you want to brew a larger amount of beer, simply divide by the volume of the recipe and multiply by the larger volume you intend to brew.
Scaling For Efficiency
Most all grain recipes will inform you of the brewhouse efficiency. The recipes I have published here have this information and I usually adjust them to 70% efficiency to make all the recipes here the same. What this percentage tells us is how much of the available fermentables we have been successful in extracting from the grains, through the brewing process and into the finished wort that is run into the fermentor.
Of course, not everyone will have the same efficiency figures and this can be down to many variables, which I hasten to add are not really that important. As long as you know your brewhouse efficiency then you can adjust the recipe to suit your needs.
If you do not know your brewhouse efficiency, take a look at this article that details how to work it your brewhouse efficiency and get a reliable figure to work with. It is a variable that can change with each batch so what we are trying to do is get a close estimate so you can calculate how much grain is needed to achieve the original gravity listed for the recipe and therefore hit the desired ABV.
Scaling A Home Brew Recipe by Efficiency
The method of scaling a recipe by efficiency is similar to scaling by volume. What is important to note though is you only need to adjust the amount of grains used in the mash.
As the efficiency is an indicator of how well fermentables are extracted from malt and grains these are the only ingredients in the recipe that need scaling. Ingredients like hops, yeast and sugars are added after the mash so they stay exactly the same.
To scale by efficiency you take each amount of the mashed grains and malts and multiply by the recipes efficiency then divide by your efficiency
As an example, in a recipe that has an efficiency of 70% and calls for 4kg of Pilsner malt, you would need to do the following to scale the recipe to 75% efficiency:
4kg * 0.7 / 0.75 = 3.73kg of Pilsner malt required at 75% efficiency.
As you can see the more efficient you get the less grain you need to use and vice versa.
Perform this calculation for each malt and grain in the mash but not for hops, yeast and sugars, that is all there is to it.
Scaling by Volume and Efficiency
If you need to scale for both volume and efficiency then just work through both scaling methods. First, scale the recipe by volume, adjusting all ingredients to your intended volume. Once all the ingredients are adjusted then scale the mash ingredients by your brewhouse efficiency.