Concrete Calculator
Calculate how many cubic yards of concrete you need for slabs, footings, and other pours.
Formula
Cubic Yards = (Length in feet Γ Width in feet Γ Thickness in feet) / 27. For cylinders: Ο Γ RadiusΒ² Γ Height / 27
How to Use
- 1Measure the length, width, and thickness (depth) of the area to be poured in feet.
- 2Convert any measurements in inches to feet by dividing by 12 (e.g., 4 inches = 0.333 feet).
- 3Multiply length Γ width Γ thickness to get cubic feet.
- 4Divide cubic feet by 27 to convert to cubic yards.
- 5Add 5-10% for waste, uneven subgrade, and form bulging to get your order quantity.
Example
Scenario
You need to pour a residential driveway that is 50 feet long, 12 feet wide, and 4 inches thick.
Calculation
Volume: 50 Γ 12 Γ 0.333 = 199.8 cubic feet. Cubic yards: 199.8 / 27 = 7.4 cubic yards. With 10% overage: 7.4 Γ 1.10 = 8.14 cubic yards.
Result
Order 8.5 cubic yards of concrete (rounding up to the nearest half yard, which is the minimum increment most batch plants sell). At $150-$175 per yard delivered, the concrete material cost will be approximately $1,275-$1,488.
Tips
- β Always round up to the nearest half or full yard when ordering β being short on a pour is far more costly than having a little excess.
- β Verify the subgrade is compacted and level before ordering β uneven ground increases the volume needed beyond your calculations.
- β Ask your ready-mix supplier about short-load fees (usually charged for orders under 8-10 yards) and factor this into your estimate.
- β For multiple pours on the same project (footings, walls, slab), calculate each element separately, then combine for total order.
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Common questions about the concrete calculator
Divide the thickness in inches by 12 to get feet. Common conversions: 4 inches = 0.333 feet, 5 inches = 0.417 feet, 6 inches = 0.5 feet, 8 inches = 0.667 feet, 10 inches = 0.833 feet, 12 inches = 1.0 foot. Using decimal feet in your calculation gives you cubic feet, which you then divide by 27 for cubic yards.
A cubic yard of standard concrete weighs approximately 3,900-4,100 pounds (about 2 tons). This is important for planning delivery access β a fully loaded 10-yard concrete truck weighs about 60,000 pounds. Verify that driveways, bridges, and site access can handle the load.
Standard residential slabs (driveways, patios, sidewalks) use 3,500-4,000 PSI concrete. Footings and foundations typically require 3,000-3,500 PSI. Garage floors and commercial slabs often require 4,000-4,500 PSI. Check your local code and structural plans for the required PSI specification.