Concrete Pier Calculator
Enter your pier size to get the concrete you need in cubic yards and bags, plus an estimated cost. Waste is included.
Concrete needed
Estimated cost
How to calculate concrete piers
A pier is a cylinder. Its volume is pi times radius squared times depth, with radius in feet. Multiply by the number of piers, then convert to cubic yards by dividing by 27.
Formula: cubic yards = pi × (diameter ÷ 2 ÷ 12)² × depth × piers × (1 + waste %) ÷ 27
Worked example: 4 piers, 12 in diameter, 3 ft deep
One pier: pi × 0.5² × 3 = 2.36 ft³. Four piers: 9.42 ft³. Add 10% waste: 10.37 ft³. Divide by 27: 0.38 cubic yards. In bags, that is 18 bags of 80 lb mix.
How deep?
Piers must go below the frost line, or frost heave will lift them. Three feet is common, but cold climates need deeper piers. Check your local code.
Common pier sizes
Cost tips
Prices on this page are editable estimates, not quotes. Get 2 to 3 local quotes before you buy, and ask if delivery is included. Delivery, tax and waste can change the total a lot. Order a little extra for cuts and breakage, and confirm final quantities with your supplier or a qualified professional.
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Frequently asked questions
How much concrete do I need for 4 piers?
Four 12 inch diameter piers at 3 ft deep need about 0.38 cubic yards with 10% waste, which is 18 bags of 80 lb mix.
How deep should deck piers go?
Below the frost line in your area, and usually at least 3 ft deep. Check your local code.
What is a sonotube?
A round cardboard form that shapes a concrete pier. Common sizes are 8, 10 and 12 inches in diameter.
Bags or ready-mix for piers?
Bags make sense for a few piers. Ready-mix only pays off for large volumes, and small loads carry short-load fees.
Are the prices accurate?
Prices are editable estimates. The defaults are typical US figures, and your local price can be higher or lower.