Quick Volumetric Question

Know there are a ton of threads that contain pieces of the info I'm seeking, but I'm just looking for a quick confirmation of my thoughts and calculations. If I were to do a 10 gallon AG batch, the grain could run up around 24 lbs depending on the recipe, displacing approximately 3 gal of space. Using 1.25 quarts per lb of grain, that would be 7.5 gal of water, which combined with the grain would put the total volume in the ballpark of 10.5 gal. So, in conclusion, I would not be able to mash in a 40 qt (10 gal) kettle with that grain bill. Does this sound accurate?

Just found the "Can I Mash It?" calculator in another thread and came up with 9.4x gallons. Little less than I estimated but I leave with the same conclusion. Thanks for reading anyhow!