I get asked this all the time, so I thought I would play around and tell you how to figure that out.

A 3/8" hose.Remember Math class and saying "when will I ever need to know - Pi x Radius Squared?"

Well look at yourself now. 3/8" = .375" diameter.

The radius is 1/2 of that.

.1875 x .1875 x 3.14

That's .110 cubic inches of space inside the 3/8" hose per inch of hose.

50' of hose is 600 inches.600 x .110 = 66 cubic inches in a 50' hose.

1 gallon has 231 cubic inches.

If you have 200' of hose, you have 66 x 4 = 264 cubic inches.

1.14 gallons to fill the hose. (add a little for the fittings at each end of each hose)