Yep quickerNu mine too. Once I started correcting the water, my eff. jumped up to 78-82% brewhouse.
Here's an improvement on Kai's method that takes into account differences in the grain bill such as highly kilned malts which have a low extract potential:
- Plug your recipe into your favorite tool at 100% brewhouse efficiency. Note the target OG.
- Multiply the OG by your post-boil volume. This gives you the total extract points available in your grain bill.
- Divide the total points available by the total pounds of grain.
- Divide the result by 45 to get the extract coefficient (% of grain mass convertable to sugar).
This extract coefficient replaces the 0.8 in Kai's formula with a more accurate extract potential of your grain bill.
A quick example, I'll use Bee Cave Brewery Haus Pale Ale
. For 5.5 gal after boil I get 1.068 out of the Tasty Brew
recipe calculator. That's 374 extract points, or 35.6 points per pound. DME is 45 points per pound so that's a coefficient of 0.791.
Google Calculator says 10.5# is 4.76 kilos and (10.5# * 1.25 quarts/#) is 12.4 liters, which gives the equation:
FW extract in Plato = (4.76 * .791) / ((4.76 * .791) + 12.4) = 23.3* Plato ~= 1.091
Does this seem reasonable?