There’s a very simple way to figure out how much concrete you need when pouring concrete. Like many construction materials, concrete is measured and sold in cubic yards. In the construction industry, you’ll hear people talking about how many yards of concrete they need, or how many yards they poured. With a few measurements and some simple math, you can figure out how many yards of concrete you need for your project.
The formula: (L'xW'xH') / 27 = cubic yards of concrete needed.
What does that mean?
Let’s do an example to demonstrate how the formula works. Let’s say we’re pouring a concrete footing for a mortared stone wall. To determine how much concrete we need, we’ll use the formula above. According to the formula, we need three measurements – the Length, measured in feet, the Width, measured in feet, and the Height, measured in feet. We’re going to multiply all three of these numbers together. Then, we’ll divide that number by 27 to see how many cubic yards of concrete we need.
For our example, let’s say our footing will be 20 feet long, 2 feet wide, and 1 foot high. Let’s do the math:
20x2x1 = 40
Now divide by 27:
40/27 = 1.48 cubic yards of concrete
Does that make sense? For pouring concrete footings 20 feet long, 2 feet wide, and 1 foot long, you would need 1.48 yards of concrete. When talking about concrete, people usually drop the ‘cubic’ and just say ‘yards.’
If I were having this concrete delivered on a concrete truck, I would order 2 yards. It’s always better to have a little extra than to run short.