How to Compute the Concrete You'll Need
by Damien Andrews
If you have a project that requires pouring concrete, then you'll need to know how to compute the concrete you'll need. Many DIY projects turn out best when concrete is poured, instead of using bricks. Some of these projects are barbecue grills, air conditioner pads, clothes line posts and flag pole receivers. So it's a good idea for you, the DIYer, to know exactly how to compute the concrete you'll need.
Here are some things you'll benefit by knowing:
• A cubic yard of concrete is 27 cubic feet of concrete.
• Most ready to mix and use concrete bags hold 2/3 of a cubic foot of concrete.
• If you want to hand mix 1 cubic yard of concrete from ready to mix and use bags of concrete, you'll need about 41 bags.
• Concrete delivery companies usually have a minimum delivery order of 2-3 cubic yards of concrete. If you order less, you'll pay an additional fee.
• Each inch of concrete can be computed as .083 feet.
• Always order an extra couple of cubic feet of concrete whenever you are having it delivered.
How to compute the concrete you'll need will require only one basic mathematical formula. All calculations are done in feet, NOT in inches. The formula is: Length x width x depth. Let's look at some examples.
How to compute the concrete you'll need if you are pouring a pad that is 4' long x 4' wide x 6" deep: 4x4x.5 = 8 cubic feet of concrete. (4x4 = 16 x .5 = 8) 8 cubic feet of concrete is about .3 cubic yards of concrete.
How to compute the concrete you'll need for a sidewalk that is 25' long x 4' wide x 4" deep: 25x4x.33 = 33 cubic feet of concrete = 1.22 cubic yards of concrete.
How to compute the concrete you'll need for a shed pad that is 14' wide x 18' long x 5" deep: 14x18x.415 = 104.58 cubic feet of concrete. Divide 104.58 by 27 to get the cubic yards of concrete: 3.873 cubic yards of concrete. NOTE: to convert the 5" depth to feet, you simply multiply 5x.083 = .415.