Concrete Pier Calculator

A round concrete pier is a cylinder, so its volume is π × Radius² × Depth. If you know the diameter — as you usually do with form tubes — the radius is simply the diameter ÷ 2. For several identical piers, Total Volume = Volume Per Pier × Number of Piers. Your waste allowance is then applied to the total to give the recommended order.

1. 1Enter the pier diameter, or pick a common diameter preset.
2. 2Enter the pier depth or concrete height.
3. 3Enter the number of identical piers.
4. 4Select a waste allowance.
5. 5Optionally enter your local concrete price.
6. 6Select Calculate.
7. 7Review the concrete volume, bags, weight and cost.

Every measurement is normalized before multiplying, so you can freely mix inches, feet, centimeters and meters. The calculator uses the full-precision value of π and rounds only for display.

Diameter is the full distance across the circular pier. Radius is half of that: Radius = Diameter ÷ 2. This matters because the cylinder formula uses radius, not diameter — entering a diameter where a radius belongs would overstate the concrete by a factor of four.

The cross-sectional area of a pier is π × radius². Because the radius is squared, volume grows faster than the diameter does. Doubling the diameter also doubles the radius, so at the same depth the circular area — and therefore the concrete volume — becomes roughly four times as large.

For example, at the same depth a 24 in pier holds about four times the concrete of a 12 in pier, because 12² = 144 and 24² = 576, and 576 ÷ 144 = 4. This is a mathematical relationship only, not a recommendation about which diameter to use.

Round concrete form tubes are sold in various diameters. Enter the diameter required by your project plans or requirements.

• 6 in
• 8 in
• 10 in
• 12 in
• 16 in
• 18 in
• 24 in

Cylindrical cardboard or fiber forms are commonly used to shape round concrete piers. The concrete quantity depends on the inside diameter of the form and the height or depth of concrete you are placing, so measure or confirm the actual form dimensions before calculating rather than relying on a nominal size.

A concrete pier is generally modeled as a solid cylinder of concrete, which is exactly what this calculator estimates. A post hole with a post set inside it is different: the volume occupied by the embedded post may need to be subtracted from the hole volume. BuildCalcWorks will use a separate Post Hole Concrete Calculator for that case.

• Confirm the inside diameter of the forms you actually have.
• Measure the concrete height separately from the total hole or excavation depth.
• Count the piers carefully — volume scales directly with the quantity.
• Check the yield printed on the bag if you plan to mix bagged concrete.
• Check supplier minimum quantities if you are considering ready-mix for a small pour.