Calculated efficiency

[jonboygentry]

Had a quick question. When you are trying to figure out your efficiency, do you use your pre-boil gravity reading or the reading after the boil is complete? Thanks for the responses!

 

[Kingbogart]

The preboil gravity is a good indicator of your mash and lauter efficiency, your post boil gravity before moving to your fermenter should be the exact same. Boiling will reduce the amount of water, but not alter the amount of sugars. If you had 90% efficiency preboil, you will still have 90% after.

If you're trying to calculate your brewhouse efficiency, the number seen on most recipes, you need the post boil gravity, and the volume going into the fermenter. This accounts for actual losses to hop absorption, dead space, and hot/cold break. This picture might help explain.

 

[DurtyChemist]

I use both.

Pre-boil gravity is mash efficiency.
Post boil could be considered brew house efficiency.