Originally Posted by patjofo
I am new to brewing. I have done a 5 gallon batch with a Brewer's Best IPA kit, waiting to bottle it in 1.5 weeks. I am not ready to make the move to all-grain but want to explore the idea of doing 2.5 gallon extract batches in a 3 gallon carboy. I've got a few questions:
Is it possible to cut 5 gallon recipes in half?
Do I still start the boil with 2.5 gallons of water (I am using a 5 gallon kettle)?
Are there any special considerations I need to make during a 2.5 gallon brew?
Can I still use a full yeast packet?
Yes, recipes are entirely scale able. Just multiply (or divide) each item by the same number.
You could start a little higher than 2.5 gal and account for boil off.
Special considerations, not really. Just that it may be difficult to get very small amounts of some items. For example, hops are very often sold 1oz at a time. For this reason, recipes often have 1oz additions.
Likely a full yeast packet would have no ill effects. It is possible to over pitch, but it should be easy enough for you to figure out the correct amount to pitch with a yeast calculator.