I know that you can hold back a small amount of wort from the primary fermenter and dose it with some yeast to determine approximate final gravity, but....if I make a starter for the batch, would I get close enough if I test the beer from the starter? It's the same yeast I intend to use in the all-grain batch, it's just the using the DME-based wort for the starter. I don't know if anyone has checked this before but I'm brewing a small batch soon and the starter is already going, so I am going to check this out. The only significant number I can derive from this is the apparent attenuation. If I apply that figure to my full batch, I should be able to approximate the final gravity. Maybe.