Enter the finished inside diameter and concrete-filled depth of a round form, the number of identical piers, a mix density and the yield printed on your concrete bag.

Formula: total ft³ = π × (diameter in ÷ 24)² × filled depth ft × pier count; yd³ = ft³ ÷ 27; short tons = yd³ × entered short tons/yd³; bags = round up(ft³ ÷ entered ft³/bag)

Worked example

Eight cylindrical piers, each 12 in across and filled 3 ft deep, need about 18.85 ft³ or 0.6981 yd³. At an illustrative 2 short tons/yd³ that is 1.396 short tons; at 0.60 ft³ per bag, round up to 32 bags.

Measure the actual filled cylinder

The diameter is the inner width that concrete fills, not the nominal outside size of a form. Count only the filled depth; widened footings or bells need a separate estimate. This calculator treats all piers as equal cylinders.

Use your product yield and density

QUIKRETE lists about 0.60 ft³ yield for one of its 80 lb concrete-mix bags; other products and bag sizes differ. The density field is an independent mix-specific estimate. A dry bag’s weight is not the same as the weight of the cured concrete volume.

Quantity is not structural design

No waste allowance, overexcavation, reinforcement displacement, footing capacity, frost-depth rule or code check is included. Add a project-specific allowance separately and have structural requirements established for the actual site.

Explore the related calculation

For a different starting point, try the delivery load calculator or return to the main calculator. Browse the complete tool directory for this site.

Reference and corrections

The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.

Found a problem? Email contact@cubicyardstotons.org.

Concrete pier volume and weight calculator

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