I will be brewing a stout in the next few weeks. The grain bill is 16 pounds of malt and an additional 4 pounds of DME. The DME will be stirred -in after mashing but before boiling. If I have calculated (and actually get) a pre-boil volume of 6.25 gallons without the DME and then add the DME to the 6.25 gallons, how many gallons will the 4 pounds of DME raise the pre-boil volume? Is there a method or calculation that I do not know about?
Thank you very much in advance.