DME will usually have 44 PPG (points per pound per gallon) and LME has about 37 PPG. The most one can extract form base malts is in between 35-38 PPG. This is assuming 100% efficiency as well. You much multiply by your brewhouse efficiency to get realiztic numbers.
For example lets say recipie has 6 lbs DME and you want to know how much 2-row grain to use.
You now need to match 264 PPG for grain assuming 75% efficiency). So...
so in between 9.25 and 10lbs of 2 row will work depending on the grains specific PPG value. I hope that made sense to anybody besides myself. Another thing to check is the color of extract used. I once converted an extract recipie to all grain and didn't notice they used dark LME. My coffee stout wasn't as black as I thought, more of a muddy brown. It tasted just as good as I wanted it too but the color was way off.
Cellar Door Brewery
Primary: Smoked Porter
Secondary: Flanders Red 2010
Kegged: 10.10.10, Robust Porter, American IPA
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