Converting Grains to Malt Extract
For the first step, convert your base malt to extract. The base malt is easy to identify as it is the largest ingredient in the beer – typically 5-10 lbs of pale malt. For example, let’s look at an all-grain ale with 8 lbs of pale malt and 1 lb of crystal malt.
The simplest base malt conversion is to just multiply the number of pounds of pale malt by 0.75 to get the pounds of liquid extract. Therefore 8 pounds of pale malt becomes 6 pounds of liquid extract.
A
n equivalent conversion for dry extract is 0.6, so 8 pounds of pale malt becomes 4.8 pounds of dry malt. A more accurate conversion would actually take the potential of the grain and extract into account when converting malt, but I will leave that topic for a future article.
To simplify things, we leave the specialty malts (1 lb of crystal) alone and switch to steeping them instead of mashing them. Some specialty malts (notably wheats, Munich malt, flaked and terrified grains) cannot be steeped and need to be replaced with a reasonable substitute. For example, those grains listed in our online grain listing as “must mash” should not be steeped. The same is true if you have a large proportion of specialty malt.
A good rule of thumb is you should steep no more than 3-5 lbs of specialty grains in the final extract recipe. Obviously you want to choose your malt extract to match the original color and style of the beer. If you are converting a wheat beer, choose a wheat extract. Beers with large amounts of Munich malt require a Munich extract. If you are making a light colored beer, pick the palest extract you can find. Pale extract is always a good starting point.
From:
http://beersmith.com/blog/2008/06/03/converting-all-grain-recipes-to-malt-extract/