Help with calculating conversion

I did my first PM today. I mashed 2# US Pale 2-row and 3# German Pilsner in 2 gallons of water for 60 minutes at roughly 151-154 degrees. I then sparged for 10 minutes in 170 degree water. I then combined the two and ended up with approximately 3.5 gallons of wort. The SG of the wort was 1.044. I calculated my efficiency at 84%. That seems high for a PM. Did I calculate something wrong? Here is my math:

2# Pale: 36x2/3.5 = 20.57
3# Pils: 37x3/3.5 = 31.7
Total: 52.27

44/52.27= .84

That depends... did you have 3.5g pre-boil or post-boil? Also, was this the amount that went into your fermenter, or did you top off to 5 gallons?

If you had 3.5 gallons post-boil, then you're right. Beertools is putting it at around 86.5% eff. but there could be a number a variables that are causing that extra %.

If you had 3.5 gallons pre-boil, then you had about 65% eff.

Both of these are assuming you didn't top off at the end.

It looks like he's only measuring against the volumes derived from the mash/sparge which is fine. To test it in BTP, you have to set the batch size to 3.5.

You can set it to 5 gallons, but then you'd have to factor in the gravity with the extract and additional water added.

85% efficiency is not unusual in such a small grain to water ratio. In other words, it's really easy to make worts at around 1.040 very efficiently.

I measured the SG preboil. In other words, as soon as I dumped the sparge water in the initial runnings I mixed it really well then took a gravity reading. Post boil, and after adding 3# DME(at beginning of boil) and topping off with water to 5.25g, I had a OG of 1.052 which was dead on where I expected.

I came up with my numbers calculated in my first post from How to Brew (JP).

So I guess I don't understand why the efficiency would be different in Suthncomforts reply for pre and post boil. Is he assuming something different than what I did?

All I'm doing is this...

I punch in that you started with 3.5 gallons pre-boil. That puts you at around 2.6 gallons post boil figuring a 60 minute boil and no other additions. So I'm basically calculating what your efficiency would have been if you were doing a 2.6 gallon batch without the addition of DME. BTP puts you at 65% efficiency for that.

This is what I concider brewhouse efficiency. The efficiency of the whole process and not just the mash. If you're calculating strictly mash efficiency, then yes, you have the calculations down pat.

Ahhh.. Ok.. Thanks for clarifying that!