Standard Reference Method (SRM ):
SRM's = Lbs Grain x Deg Lovibond) / Total Volume in US Gallons
So if you used 10 pounds of 2 row grain that is 1.9 Lovibond then you would multiply lbs of grain by Lovibond to get your SRM. Then add all the SRM's and divided by total batch volume by total US Gallons. Here is an example below:
(10.00 Lbs Grain x 1.9 Lovibond) = 19.0 SRM's
(0.50 Lbs Grain x 10.0 Lovibond) = 5 SRM's
(19 + 5) / 5 gallons = 4.8 SRM's
Total SRM's = 19 + 5 + 4.8 = 28.9
Wouldn't that be MCU as defined here
A first iteration at estimating beer color involved simply calculating the Malt Color Units (MCUs) of a recipe.
* MCU = (Weight of grain in lbs) * (Color of grain in degrees lovibond) / (volume in gallons)
For multiple grain additions, you can simply calculate the MCU for each addition and add them together. MCU provides a good estimate of SRM color for light beers, but starts to diverge as beer color exceeds 6-8 SRM, because light absorbance is logarithmic and not linear. For a more accurate estimate that holds for darker beers up to about 50 SRM, we turn to the Morey equation:
* SRM color = 1.4922 * (MCU ** 0.6859)
The Morey equation provides an excellent estimate of beer color throughout the range from 1-50 SRM, and is the one used by most brewers today.
In this case the beer would have an MCU of 28.9 which gives a SRM color of 15. I noticed this when I saw the calculated color of a recipe vary widely from what qBrew, beercalculus, and the brew-builder at BMW were indicating. The 30 your sheet indicates for my recipe would actually be an 15 (which matches other calculators I have used).
Any chance of getting an unprotected copy for tinkering?