Concrete Calculator (Square, Circular, Tube, Curb, Stairs)

Patios/walkways commonly use \(4\) inches. Driveways/garages often use \(6\) inches for heavier loads. Always check local codes and soil conditions.

Convert thickness: \(4\ \text{in}=\frac{4}{12}=0.33\ \text{ft}\). Example \(20\times20\): \[ V = 20 \times 20 \times 0.33 = 132\ \text{ft}^3 \] \[ V=\frac{132}{27}=4.89\ \text{yd}^3 \]

At 4 inches thick: \[ V = 20 \times 20 \times \frac{4}{12} = 133.33\ \text{ft}^3 \] \[ V=\frac{133.33}{27}=4.94\ \text{yd}^3 \] Add \(5\%-10\%\) waste.

Split the shape into rectangles/squares, compute each with \(V=L\times W\times H\), then add them. Curves can be approximated using segments.

Example: \[ V = 30 \times 1 \times 2 = 60\ \text{ft}^3 \] \[ V=\frac{60}{27}=2.22\ \text{yd}^3 \]

Use cylinder volume: \[ V=\pi r^2 h \] Example: 12-inch diameter \(\Rightarrow r=6\ \text{in}=0.5\ \text{ft}\), \(h=4\ \text{ft}\): \[ V=3.14\times(0.5)^2\times 4=3.14\ \text{ft}^3 \] \[ V=\frac{3.14}{27}=0.12\ \text{yd}^3 \]

Same as above (per hole): \[ V=3.14\times(0.5)^2\times 4=3.14\ \text{ft}^3 \] \[ V=\frac{3.14}{27}=0.12\ \text{yd}^3 \]

Typical 6-inch diameter \(\Rightarrow r=3\ \text{in}=0.25\ \text{ft}\), depth \(=2\ \text{ft}\): \[ V=3.14\times(0.25)^2\times 2=0.39\ \text{ft}^3 \] \[ V=\frac{0.39}{27}=0.014\ \text{yd}^3 \]

For each pier: \[ V=\pi r^2 h \] Add all pier volumes and convert: \[ \text{yd}^3=\frac{\text{ft}^3}{27} \]

Use: \[ V=\pi r^2 t \] Example: 10-ft diameter \(\Rightarrow r=5\), thickness \(6\ \text{in}=0.5\ \text{ft}\): \[ V=3.14\times 5^2\times 0.5=39.25\ \text{ft}^3 \] \[ V=\frac{39.25}{27}=1.45\ \text{yd}^3 \]

20-ft diameter \(\Rightarrow r=10\), thickness \(4\ \text{in}=\frac{4}{12}\ \text{ft}\): \[ V=3.14\times 10^2\times \frac{4}{12}=104.67\ \text{ft}^3 \] \[ V=\frac{104.67}{27}=3.88\ \text{yd}^3 \]

A slab is solid; a tube is hollow: \[ V=\pi\left(R^2-r^2\right)h \] (outer minus inner).

One common estimating approach is curb + gutter components: \[ V_{\text{curb}}=\text{Depth}\times(\text{Height}+\text{Flag Thickness})\times \text{Length} \] \[ V_{\text{gutter}}=\text{Gutter Width}\times \text{Flag Thickness}\times \text{Length} \] Total: \[ V_{\text{total}}=V_{\text{curb}}+V_{\text{gutter}} \] Then convert \(\text{yd}^3=\frac{\text{ft}^3}{27}\).

Curb profiles vary by region/standard drawings. A commonly used estimate example is around 6 inches wide and 18 inches tall, but always verify local details.

If cross-section area \(A=0.75\ \text{ft}^2\) and length \(L=100\ \text{ft}\): \[ V=A\times L=0.75\times 100=75\ \text{ft}^3 \] \[ V=\frac{75}{27}=2.78\ \text{yd}^3 \] Add \(5\%-10\%\) waste.

\[ V=L\times H\times T \] Example: \[ V=20\times 3\times 1=60\ \text{ft}^3 \] \[ V=\frac{60}{27}=2.22\ \text{yd}^3 \]

Rebar volume is usually negligible for estimating concrete. Focus on dimensions and add \(5\%-10\%\) extra for waste.

\[ V=10\times 2\times 1=20\ \text{ft}^3 \] \[ V=\frac{20}{27}=0.74\ \text{yd}^3 \]

A quick and more accurate stepped model: \[ V_{\text{steps}} = W \times G \times h \times \frac{n(n+1)}{2} \] Landing approximation: \[ V_{\text{landing}} \approx W \times P \times h \] Total: \[ V_{\text{total}} = V_{\text{steps}} + V_{\text{landing}} \]

Estimate steps + landing separately, then convert cubic feet to cubic yards by dividing by 27: \[ \text{yd}^3=\frac{\text{ft}^3}{27} \] Add \(5\%-10\%\) waste for outdoor pours.

Often \(0.5\)–\(1.0\ \text{yd}^3\) depending on size. Measure run, rise, width, and steps for accurate results.

They’re accurate if inputs are correct. For complex geometry or structural work, verify manually or consult a professional.

Break the project into shapes, calculate each volume, then sum the results. Many calculators support combining volumes.

Look for an app/web tool that supports slabs, footings, round holes, and unit conversions. Web calculators are often enough for most users.

\[ \text{Cost} = (\text{Total yd}^3)\times(\text{Price per yd}^3) + \text{Delivery/fees} \] Prices vary by region.

Take multiple depth readings and use the average thickness in your volume calculation.

Base material is separate from concrete volume. It supports the slab but doesn’t change concrete volume unless slab thickness changes.

Typical yields: \(60\text{lb}\approx 0.45\ \text{ft}^3\), \(80\text{lb}\approx 0.60\ \text{ft}^3\). Bags needed: \[ \text{Bags}=\frac{\text{Total ft}^3}{\text{Yield per bag}} \] Example: \(100\ \text{ft}^3 \div 0.45 \approx 222\) bags (60lb).

At 6 inches (\(0.5\ \text{ft}\)) thick: \[ V=400\times 0.5=200\ \text{ft}^3 \] \[ V=\frac{200}{27}=7.41\ \text{yd}^3 \] Add \(5\%-10\%\) waste.