Grain and Partial Extract Brewing

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.

About 1.8 liters or .47 gal. This is based off of a 1 liter stater needing 900ml water and 100g of DME. It’s close enough.

Stevie,

I really appreciate you answering my questions.
You always answer with good info and quickly!

You da man - or King of Homebrew.

Mickeymoondawg