I've been away from this site for a while and I see there has been quite a bit of discussion. Let me be clear, I do not calculate my efficiency for every batch. I do it every once in a while and usually come up with the same numbers.

This is the formula that I use for Mash Efficiency. Perhaps my terminology is not correct, perhaps my math is off. This was my understanding. Please correct me.

grain weight x Lab max (.80) / total mash water + (grain weight x lab max) = X

hydrometer reading of first runnings / X = Mash Efficiency

Formula for Brewhouse Efficiency. The extract points are from a chart in Ray Daniels book page 31. Example one pound of pale malt would yield 35-37 points.

Total extract potential in points / gallons collected = X

Hydrometer reading of wort collected / X = Brewhouse efficiency

Ok, I am ready for a critique.