Concrete Slab Calculator 20' x 20' x 6"

A 20 x 20 foot concrete slab 6 inches thick is 400 sq ft and needs 200 cubic feet of concrete: 7.4 cubic yards. Change any size to recalculate. The calculator comes filled in with 20 ft x 20 ft x 6 in. Enter your own width, length and thickness to get the surface area and the volume of concrete in cubic feet and cubic yards, with the concrete added to the materials, ready to price the job in a GetCost estimate. How to calculate it: multiply the length by the width by the thickness, all in feet (6 inches = 0.5 ft): 20 x 20 x 0.5 = 200 cubic feet. Divide by 27 to get cubic yards: 200 / 27 = 7.4. That is the exact volume - order about 10% more for waste, spills and uneven ground (about 8.1 cubic yards here). An 80 lb bag of concrete mix makes about 0.6 cubic feet, so this slab would take over 330 bags: order ready-mix by the yard. Other sizes: the 10 x 10 x 6 inch and 10 x 10 x 4 inch slab calculators, or the Concrete Slab Calculator for any size, with labor.

• Concrete Slab Calculator 20' x 20' x 6"
• Width
• Length
• Thickness
• Concrete
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