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Material Calculators

Construction calculators

Slabs, footings and columns — in cubic yards, bags and cost.

ft
ft
in
%
$

Optional — ready-mix runs about $125–$165 per yard.

Concrete needed

3.26 cubic yards

80 lb bags

147

Ready-mix

3.5 yd³

Sold in ¼-yard steps

Weight

6.6 tons

Metric

2.49 m³

147 bags is hours of mixing — past about a cubic yard, ready-mix is usually cheaper.

Show the math
  • Volume 20 × 12 × 0.333 ft = 80 ft³
  • Plus 10% waste 88 ft³
  • To cubic yards 88 ÷ 27 = 3.26 yd³
  • Bags 88 ÷ 0.6 = 147

Updates as you type, in your browser. Figures used

More calculators

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Quick answers

13 questions

Frequently asked questions

How accurate are these calculators?

The geometry is exact. Material weights, bag yields and paint spread rates are published industry figures, listed on the how we calculate page, and every one of them can be changed on the calculator.

Why is extra material added?

Ground is uneven, material spills and tile gets cut. Each calculator adds a waste allowance you can change, and the maths shows the figure before and after.

Do they work in metric?

Yes. Switch the toggle above any calculator and the inputs and results convert.

Is anything I type sent anywhere?

No. Everything runs in your browser.