How to estimate concrete removal: area, volume and weight

Three measurements and two conversions give you most of what you need to understand a concrete removal quote.

Step 1: area

Multiply length by width, in feet. A 20 by 20 foot slab is 400 square feet.

Step 2: volume

Convert the thickness from inches to feet by dividing by 12, then multiply by the area. A 4 inch slab is one third of a foot thick, so 400 square feet times one third is about 133 cubic feet. Divide by 27 to get cubic yards: about 4.9 cubic yards.

Step 3: weight

Ordinary concrete weighs roughly 150 pounds per cubic foot, which is about 4,000 pounds, or 2 tons, per cubic yard. So the example slab is about 10 tons.

Step 4: loads

Divide the weight by what a truck or container can carry. Concrete is heavy, so loads are often limited by weight before they are full. Broken pieces also take up more space than the original slab.

Worked example

Real slabs vary. Driveways and garage floors are often thicker than 4 inches, and reinforced concrete is harder to break. Measure the thickness at an edge or a crack if you can.