How to Calculate True Recipe Volume

[igliashon]

Okay, hear me out--I'm pretty sure this question is more complicated than it sounds. When we say a recipe is x number of gallons (5 gallons, 3 gallons, etc.), are we talking gallons of wort in the kettle at the end of the boil, gallons of wort at the start of the boil, gallons of wort entering the carboy after post-boil whirlpool/filtering, or gallons of finished beer after racking off the yeast?

Like, let's say I'm brewing a simple extract recipe, with 3 gallons of water, 4 pounds of LME, and maybe 2 oz of hops. Is this a "3 gallon" recipe? Or is it a "2.5 gallon" recipe?

 

[Golddiggie]

I count mine as how much I get after fermentation is complete and its going into kegs. So, most of the time, I make 6 gallon batches. BeerSmith 2.1 helps me too calculate post boil volumes, amount into primary, etc. so that I reach my goal.

 

[MalFet]

When you see something listed as a "6 gallon batch", that generally means volume in kettle at the end of boil. Other figures don't convert very well from system to system.

 

[evrose]

When you see something listed as a "6 gallon batch", that generally means volume in kettle at the end of boil. Other figures don't convert very well from system to system.

Not if you do a partial boil and top off in the fermenter - which a lot of us have to do because we don't have a large enough boil pot.

The volume listed in a recipe is the volume in the fermenter when the yeast is pitched.

 

[MalFet]

Not if you do a partial boil and top off in the fermenter - which a lot of us have to do because we don't have a large enough boil pot.

The volume listed in a recipe is the volume in the fermenter when the yeast is pitched.

Good point, though then it gets even more complicated.

The ingredients in a recipe target a certain volume of wort. If you are leaving any volume of wort in the kettle due to deadspace or trub, then figuring out how much top off water you need to add will require some amount of algebra.

In other words, if you're topping off, a recipe for a "6 gallon batch" could never actually involve a volume of 6 gallons.

 

[JohnnySardonic]

IMO the batch size is always assuming a full boil, and is referring to the amount of wort in the fermenter prior to the yeast being pitched.

This makes it difficult/inconvenient for those doing partial boils to reproduce recipes, but I think that just comes with the territory.

But, that's just how I look at it.

 

[Budzu]

The important number, the one that affects gravity and your calculations of the brewing, is the volume in the kettle at the end of boil. To really dial-in your brewing system you need to work with 2 volumes and gravities, pre-boil and post-boil. MOST recipes are listed by their post-boil volumes, not finished volumes.

Volume losses after that are variable. It will never stay the same because you're always using different amounts of hops etc. which will keep more or less in the kettle after racking to fermenter. Different yeasts also will keep more or less wort volume in the cake. The cake may be fluffy or tight, changing your finishing volume from batch to batch. I don't worry about those numbers, just make sure you have a little more than enough in your post-boil.

In your example in your OP, it wouldn't be called a 3 gal recipe if it involved a total of 3 gal. of water, its a 3 gal recipe if it finishes the boil at 3 gallons.

 

[igliashon]

Okay, so looks like we're talking volume post-boil. Thanks, guys.