Halving a 5 gallon recipe

Hi all,

I’m pretty new to brewing. I’ve done a couple 1 Gallon extract kits. I’m looking to slighty up production to make 2.5/3 gallon batches, without investing in all new equip. My question is if I buy a 5 gallon kit, can I simply cut all the ingredients in the instructions in half? So starting with the initial boil water, cut it from 2.5G to 1.25G? Then halve the extract, hops etc? Can I then top off the water to the wort and bring it to 2.5 to 3 Gallons in the fermenter? Sorry if these are idiot questions, but I am new :smile:

This is not an idiot question. Scaling a recipe can get complicated. The basic answer is you can proportion the ingredients of a five gallon kit to what you want to end up with in the fermentor. If you want 2.5 gallons in the fermentor just divide the ingredients in half.

The complication is that hop oil isomerization may be affected by the specific gravity of the wort in the boil kettle. Lower SG worts will isomerize more hop oils resulting in increased IBUs of the beer. This would be more noticeable in highly hopped beers than beers that have little hop bitterness. You can ignore the potential difference in IBUs if you wouldn’t mind having the beer turn out a little more hoppy.

A good way to determine what your final product will be, compared to the original recipe volume, is to use a recipe builder like this one.

Enter the ingredients for the full volume recipe and boil volume, then enter the ingredients and boil volume for the batch size you want to make. You can then compare the two recipes.

I will also mention that some kit instructions sometimes indicate a short primary time and racking to a secondary vessel. A longer primary time and no secondary does have benefits.

Also the boil loss will remain the same, usually about a gallon an hour.

If the kit uses liquid malt extract, there may be some challenges splitting the LME. I don’t know of a good way to split 6lb LME jugs into two parts - but maybe someone else does.

I can’t just weigh 3 lbs of the LME? Not that easy?

You can also measure it in inches. Three pounds of LME, in a straight sided jug, will be one-half the height of six pounds. I had done this before I had a scale.

So did you pour approximately 1/2 out of the jug into the kettle after warming the LME? If so, any special tips? How did you store the other half?

There are some LMEs that don’t have matching DMEs. So I’m curious about what you did as my experiences with using a full jug of LME have been positive (end result), but somewhat sticky/messy :smile: during the brewing process.

I’ve used partial containers of LME and DME. It’s just a matter of measuring things out. I always would store leftover LME in the fridge, but I discovered that it doesn’t last very long once it’s been opened, so if you go the LME route, I’d make sure to use the rest of the jug within about a month or so at the most.