The answer is, to the best of my knowledge, 313.25!
I think that from year to year the formulation of Christmas Ale can vary slightly depending upon the availability and cost of the ingredients they use. I have noticed that the article that I wrote last year about the number of calories in Christmas Ale is starting to become popular again, so I decided to revisit my calculations and update them for this years formulation.
The number that I came up with this year is significantly higher than it was last year. I would expect an increase, since the alcohol content is up (from 6% to 7.5%), but this seems a little high (the alcohol content is up by 25%, but the calories from my calculation is up by 30%). If you are counting your calories, but don't want to limit your Christmas Ale intake by too much, then maybe you should just average this years number with last years. I mean, it's Christmas Ale, it's worth it.
Alcohol(by weight) = 76.08(OG-FG) / (1.775-OG)
7.5 = 76.08(x-1.022) / (1.775-x)
7.5 X 1.775 - 7.5x = 76.08x - 76.08 X 1.022
13.3125 + (76.08 X 1.022) = 76.08x + 7.5x
91.1 = 83.58x
x = 1.090 (in 2008 it was 1.070)
Now, we can calculate the calories:
C = 851(1.090-1)(1.090+3)
C = 313.25 (in 2008 it was 242.45)
As always, if anyone sees a error in the calculations (or if a GLBC Brewmaster would like to correct me), please feel free to post a comment or otherwise contact me.