Round concrete volume

How it is calculated

V = π × (diameter / 2)² × height × count; yd³ = ft³ / 27.

Keep the full result when using it in another calculation. Results show up to three decimal places; very small positive results use scientific notation (for example, 1e-6). No extra material for waste is added.

Measure the filled cylinder

Enter the inside diameter of the space that will contain concrete, not the outside diameter of the form. Measure the fill height along the centerline, at a right angle to the circular base. If you have several columns, use the count only when their dimensions match.

The calculator converts diameter to radius by dividing it by two, then uses the circular area for the full height. A tapered form or a column with a changing diameter needs a different shape model.

Check the effect of diameter

For a 2 ft inside diameter and a 3 ft fill height, one cylinder contains about 9.425 ft³. The result grows with the square of the diameter, so a small diameter error has a larger effect on volume than the same percentage error in height.

Use the same volume unit in the next estimate. For a bag count, divide by the exact product’s mixed yield in matching units and round the package count up only after calculating the total need.

Before you use the result

• Use the actual inside diameter of the space being filled, which may differ from the form’s nominal size. The calculation assumes the entire circular section is filled.
• The diameter must stay the same from bottom to top. Measure height perpendicular to the base. Multiple components must have identical dimensions and must not overlap.

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