quick efficiency check required please

8.5 UK lbs of pale malt mashed in 4 UK gals of water, rinsed with a further 4 UK gals, a 45 minute boil left me with 5.5 UK gallons with SG 12.7 BRIX, thanks.

How big are UK gallons and pounds?

i would say 82 Polish %

I get 107% assuming 1.037 ppg for the pale ale malt, 1.2 US gallons to 1 UK gallon and 1 US pound to 1 UK pound.

1 imperial gallon is 1.2 US gallon
1 lb is 1 lb
The yield for UK pale malt is 38 points per pound per US gallon (for every batch of UK pale malt I've ever used where I've got an analysis).
Promash and Beersmith translate 12.7 brix to 1.049.
So 8.5 (lbs) * 38 (yield) / 6.6 (US gallons) = 49 points per gallon or an SG of 1.049.
So from your figures, you got 100% efficiency.
I think you should check your measurements.

-a.

What was your pre-boil volume of wort? ajf's calculations are based on your post-boil volume.

He said "a 45 minute boil left me with 5.5 UK gallons with SG 12.7 BRIX"
That's obviously a post boil volume.

-a.

Bob, come back and say thanks to all the nice people who took the time to do your homework for you.

tektonjp - you are right, and I have, I was out testing the commercial beer market in the UK yesterday ! I clearly cannot be getting 100% but I mash with 5 pints of water to each pound of pale malt and sparge with another 3 gallons approx. After 5 days the beer is nearly ready to bottle, .....

BOBTHEukBREWER said:

tektonjp - you are right, and I have, I was out testing the commercial beer market in the UK yesterday ! I clearly cannot be getting 100% but I mash with 5 pints of water to each pound of pale malt and sparge with another 3 gallons approx. After 5 days the beer is nearly ready to bottle, .....

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Don't bottle it so soon. The yeast will do a lot more work clearing the beer and cleaning up off flavors naturally produced during fermentation. Leave the beer in primary for at least another week. 3-4 weeks total would be better.

I bottle asap - the yeast will do the same job in each bottle.