1.78 cu. yds.
You will need 17.8 cubic yards of concrete.
10.67 Cubic Yards
10 yards
6.67 Cubic Yards
20 feet x 20 ft x .3333 ft = 133.33 cubic feet / 27 cubic feet per yard = 4.94 cubic yards
You will need 17.8 cubic yards of concrete.
8.25 cubic yards of concrete
10.67 Cubic Yards
151/9 cubic yards for every 12 inches thick
532.4074 yards of concrete, round up to 533 yards.
6.94 Cubic Yards
3.6 cubic yards will be enough.
10 yards
6.67 Cubic Yards
Depends on how thick it is. At 4 inches thick, you would nee about 5.5 cubic yards adjusting for safety. At 6 inches, you'd need about 8 cubic yards. You can play with different thicknesses with the linked concrete pad calculator.
4.074 cubic yards for every foot the slab is thick.
20 feet x 20 ft x .3333 ft = 133.33 cubic feet / 27 cubic feet per yard = 4.94 cubic yards