What is the formula for figuring how many yards of concrete to use?

Answer 1

The formula is:

(Length x Width x Height) / 27 - All measurements in feet

example - a 10' x 10' x 6" thick patio

10 x 10 x .5 = 50 cubic feet

50 cf / 27 = 1.85 cubic yards

for round applications (post holes etc..) take the area of the circle x depth