That would depend on the dimensions of the area being excavated.
For a 4-inch depth: 4.75 cubic yards. For a 6-inch depth: 7.1 cubic yards.
77/9 cubic yards for every inch of depth.
If you pour to a 4" depth, you will need at least 24.89 cubic yards. If you use a 6" depth, you will need at least 37.33 cubic yards.
Would need to know the depth to give you the correct answer.
You cant convert 20 yards into cubic feet. You need lenght, breadth and depth to calculate the cubic area.
2.2469 cubic yards for each inch of depth.
You already have a square yard of topsoil, so how does 20 inches of depth get you the volume of topsoil? There are 36 inches in a yard, and you have 20 inches of topsoil depth that's 20/36ths of a yard of topsoil depth. That's 0.555... or about 0.56 yards. The volume of topsoil is 1 yard by 1 yard by 0.56 yards, or about 0.56 cubic yards of topsoil.
If you pour it to a depth of 4", you will need a minimum of 9.14 cubic yards.
For a 4-inch depth you need at least 14.81 cubic yards.
At a poured depth of 4 inches, you will need 4.94 cubic yards.
Assuming you pour to a depth of 4", you will need 1/3 cubic yards. If you go to 6" depth, you will need about 1/2 cubic yard.
5 gallons can be removed from 1 cubic yard 40.395 times. (rounded)