Reducing Recipe Quantity

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Sep 20, 2017
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Alliston, Ontario
Hello All,

I'm writing this even before I brew my first batch (ever) so go easy on me.

I ultimately want to brew smaller batches, approx 2.5 gals. As much as I want (and can) brew the typical 5gal recipes, I just won't be able to drink it all, and I don't want it to go to waste. I also want to brew more frequently, to try out all of the fantastic recipes flying around here.

So....What do I do to adjust a recipe? Is it as simple as reducing the grain and hop weights of the recipe? Or do I need to adjust brew times, temperatures or take other things into consideration? Is there a tool/calculator that can assist in adjustments like this?

Thanks for the replies and wisdom!

Welcome to home brewing and to Homebrew Talk. Yes, you can generally scale the recipies proportionally based on the batch size.
You definitely can, I do. Cut the ingredient amounts, but keep the temps and timing the same.

As far as tools to help...I use Brewer's Friend. Lots of people use Beersmith.
There's lots of sites and apps that will help. Brewers friend and brew toad are pretty good. You can search for Wort or Biermacht apps for your phone too. They're very simple to use.
I suggest using Brewtoad for a free and reasonably accurate option. You can input 5 or 10 gal recipes from the forum and then easily scale them to 2.5 gallons.
I use Brewers Friend to adjust 5G recipes down to 2.25 or 2.5G. You may need to tweak some of the grain and hop amounts to maintain the IBUs and OG of the original recipe. Other things like mash temp and time, boil time, etc stay the same. You just have to figure out how much water to use. I just kind of estimated based on what I expected to lose from the mash and my boil off rate. But there are calculators for that too.
I would say you can cut all the volumes and weights in half, EXCEPT the pre-boil volume. You need to figure out your boil-off compared to the boil-off in the original recipe. Keep all times and temperatures the same.

For example, assume that the original recipe uses a 1 gallon/hour boil-off, starting with 6.5 gallons to get 5.5 gallons post-boil after a 60-minute boil. If you cut everything in half, your numbers would be 3.25 gallons pre-boil and 2.75 gallons post-boil for a 60-minute boil, which implies a 0.5 gallon/hour boil-off. You may not actually have a 0.5 gallon/hour boil-off with your equipment.

So, try boiling 3.75 gallons of water for an hour, then measuring your post-boil volume. (Boil-off of water vs. wort will be somewhat different, but this will get you close.)

Next, divide the original recipe's post-boil volume by 2. This is your expected post-boil volume.

Now, add the boil-off you measured to your expected post-boil volume. This is the pre-boil volume you need to use.
As others stated it’s just a matter of reducing your ingredients. The time will be the same weather you’re making 1 gallon or 30bbl. I’d recommend something like beer smith to recalculate your recipe.

I must say however, that I get confused when I hear this though. Most of my customers who are doing smaller batches do so because they are apartment brewers and don’t have much space for larger equipment, or they are on the stovetop and don’t want to invest in a larger pot or wort chiller. I totally understand these reasons for small batch brewing, but being afraid of not going through the beer quickly enough is never really a concern. Even before we were brewing on a commercial level we would brew 10 gallons once or twice a week for 10 years and found that we’d kick kegs way too fast. Now we brew 15 gallon batches once a week and find we kick 3 kegs within 6-7 days. Trust me you will always find people willing to rid you of unwanted beer.

Also remember it takes the same amount of time to brew 2 gallons as it does 5 gallons. I ask my new brewers this question: is it worth your time to spend 4-6 hours for 10 bottles of beer? I always recommend doing a full 5 gallon batch if you have the capability