Concrete Calculator
Calculate cubic yards of concrete for slabs, footings, or columns. Tells you how many 60 lb and 80 lb bags you need.
Pour details
Concrete needed
1.23 cubic yards
That is 33.33 cu ft or 0.94 m^3.
Bags of pre-mix (with 10% waste):
60 lb bags
82 (or 75 without waste)
80 lb bags
62 (or 56 without waste)
Frequently Asked Questions about the Concrete Calculator
How thick should a concrete slab be?
A standard patio or walkway uses 4 inches. Residential driveways need 4 to 6 inches. Heavy-duty slabs (RV pads, garage floors) call for 6 to 8 inches over a compacted gravel base.
How many bags of concrete are in a cubic yard?
One cubic yard equals 27 cubic feet. That works out to 60 bags of 60 lb mix (0.45 cuft each) or 45 bags of 80 lb mix (0.6 cuft each). Above roughly 1 cubic yard, ready-mix delivery is usually cheaper.
What is the density of cured concrete?
Standard cured concrete weighs about 150 lbs per cubic foot, or roughly 4,050 lbs (just over 2 tons) per cubic yard. Lightweight mixes run 90 to 115 lbs per cubic foot.
Why does the calculator add 10 percent waste?
Spillage, uneven subgrade, over-excavation, and form deflection all consume extra concrete. A 10 percent buffer protects you from running short mid-pour, which would leave a cold joint in the slab.
How do I calculate concrete for a round column?
Use pi x (diameter/2)^2 x height, all in feet, to get cubic feet. Divide by 27 for cubic yards. A 1 ft diameter, 8 ft tall column needs about 6.28 cubic feet, or 0.23 cubic yards.
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