How the concrete calculator works
Enter the length, width, and thickness of a rectangular slab, pad, or footing. The calculator converts thickness from inches to feet and estimates volume.
Formula
Volume = length × width × thickness in feet
Order volume = volume × 1.10
Cubic yards = order volume ÷ 27
Example
A 10 ft × 10 ft slab at 4 inches thick is about 33.33 cubic feet, or about 1.36 cubic yards after the built-in 10% planning allowance.
Assumptions and material notes
The 10% allowance is a general planning estimate, not a universal waste factor. Slopes, uneven subgrade, forms, over-excavation, and supplier minimums can change the order quantity.
Frequently asked questions
Why add 10%?
It provides a simple planning allowance for minor variation and waste. Your project may need more or less.
How many cubic yards are in a cubic foot?
One cubic yard equals 27 cubic feet.
Does this calculate ready-mix truck loads?
No. Confirm truck minimums and delivery requirements with your supplier.
Can I use decimal dimensions?
Yes.
Should I verify the order quantity with my supplier?
Yes. Confirm the final quantity, minimum order, delivery requirements, and mix specifications with your concrete supplier.
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Disclaimer: Estimates are for planning purposes only. Actual material requirements may vary based on site conditions, material specifications, installation methods, waste, and local requirements. Always verify quantities with your supplier or qualified professional before purchasing materials.