You will need 1.23 cubic yards.
You need 82/3 [cubic] yards for every foot deep that it has to be.
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If the slab is the standard 4" deep, you will need at least 8.89 cubic yards.
At a poured depth of 4 inches, you will need 4.94 cubic yards.
You will need 0.56 cubic yards of concrete.
You will need 17.8 cubic yards of concrete.
how many yards of concrete will i need to do a 20 x20 x4 slab
1.85 cubic yards.
You will need 1.23 cubic yards.
10 yards
At 4" thick you will need 1.23 cubic yards.
2.96 Cubic Yards
You will need 3.6 cubic yards.
You will need 27.6 cubic yards of cement.
40 yards.
3.56 Cubic Yards