Andrew,
I didn't see a reply but my spreadsheet has this formula:
=E5*F5*($C$51))/0.04
Where E5 is degrees Lovibond, F5 is the expected OG, and $C$51 is a
color factor (set to 125% to account for darkening during the boil).
Example: A5 = 18, E5=1.6, F5= 0.022, color is 1.1.
Using expected OG does take in account the batch size and brewery
extract efficiency. The above is the expected color for 2-row in a 21
gallon batch of wit.
Not sure if I ever looked to see how close the calculated color compares
to the final product.
rick
I found this equation for estimating beer color:
SRM = 1.4922 [(MCU) ^ 0.6859] - for values of SRM < 50
Where MCU = Malt Color (dL) * weight (lbs) / volume (gals)
From a Brewing Techniques log:
http://www.brewingtechniques.com/brewingtechniques/beerslaw/morey.html
Andrew