Creating 2.5 gal batches from 5 gal recipes

[rdbrett]

Noob question. I'd like to make some 2.5 gal batches of some beers I want to try. I do AG BIAB. What are the concerns/considerations for cutting a known recipe in half? Dumb question? Use same amount of yeast? Can ferment in same vessel? Can you still aim for same gravity readings? Any help is appreciated.

 

[WiseEyes]

1. hop utilization does not perfectly scale. Use free brewing software (do a google search) to scale your recipes.
2. fermenting in the same vessel that you use for 5 gallon batches probably would be ok but that is a lot of headspace and that might be a concern for some people. I say that you will be fine because the co2 created by fermintation will purge the air out of the fermentation vessel.
3. as for yeast go to mrmalty.com and pitch the appropriate amount of yeast for the gravity and style.
4. Gravity should scale with your recipe again find a free recipe calulator and if your serious about brewing invest in something like http://www.brewtarget.org/ is free or http://beersmith.com/ is not.