Concrete Column & Pier Calculator

How it's calculated

The calculator treats a column or pier as a solid cylinder — π × (diameter ÷ 2)² × height — with no subtraction, since a column or pier is a solid pour rather than a ring around a post the way a post hole is. That volume is multiplied by the quantity you enter, so a whole row of identical piers calculates at once instead of one at a time. A waste percentage is added on top to cover spillage and mixing loss, and the adjusted cubic yardage is multiplied by concrete's density to get the weight in tons. Bag counts divide the adjusted cubic feet by each bag's yield; ready-mix truckloads divide the adjusted cubic yards by the truck's capacity.

Worked example

Four deck piers, each poured in a 12-inch-diameter tube form, 48 inches tall: per pier, volume = π × (6 ÷ 12)² × (48 ÷ 12) = π × 0.25 × 4 = 3.14 cubic feet. Across all four piers (quantity = 4): 3.14 × 4 = 12.57 cubic feet. In cubic yards, that's 12.57 ÷ 27 = 0.47 yd³. Adding a 10% waste factor: 0.47 × 1.10 = 0.51 yd³. At 2.02 tons per cubic yard, that's 0.51 × 2.02 = 1.03 tons — or 1.00–1.04 tons across the 1.95–2.03 density range. In 60 lb bags, the adjusted 13.82 cu ft (12.57 × 1.10) needs 31 bags for all four piers combined — close enough to the half-yard bulk-delivery threshold that ready-mix is worth pricing out too.

How deep should it be?

A pier and a footing are often confused, but they're different structural elements. A footing is the buried base that spreads a structure's load into the soil — wide and shallow relative to what sits on it. A pier is the vertical concrete column that carries load from a post or beam down to that footing, and it's often what a cardboard tube form pours: a round, plumb column rather than the wide, flat pad a footing calculator handles. Many deck and porch designs pour the footing and pier as one continuous monolithic element — a wide base flaring out at the bottom of the same hole a tube form sits in — in which case this calculator's cylinder geometry only captures the pier portion above where it flares, not the full combined shape; check your specific detail before assuming the numbers here cover the whole pour. How wide and how tall a column or pier needs to be is entirely a structural decision this calculator doesn't make. Diameter is set by the load it carries — a porch roof column supports far more than a light deck rail post — and by your local code's minimum sizing for that load. Height below grade is set by your local frost depth, so the pier's base sits below the frost line and isn't heaved by seasonal freeze-thaw; height above grade is whatever your design calls for. All of this is a building-department or engineer's call, not something a generic calculator should estimate — check your local building department or the International Residential Code's provisions for the actual numbers your project needs before you order forms or dig. Forms matter more here than for a footing or post hole poured against undisturbed soil. Below grade, the surrounding earth itself often acts as the form, the same way a post hole's walls do. Above grade, though, wet concrete has nothing to hold its shape against — it needs a form, and cardboard tube forms (often sold under the brand name Sonotube) are the standard choice for a round column or pier: a spiral-wound cardboard tube, sized to standard diameters, that's set plumb, braced so it doesn't shift or bow under the weight of wet concrete, filled, and stripped away once the pour has cured enough to hold its own shape. A form that isn't plumb or braced can bulge, lean, or crack during the pour, which is a labor problem this calculator's math can't help with — get the form right before you're worried about the volume.

Common mistakes

• –Assuming a pier's diameter or height without checking your local code or an engineer's sizing — both are set by structural load and soil bearing capacity, not a rule of thumb.
• –Confusing a pier with its footing. A footing spreads load into the soil; a pier carries load up from the footing to grade or above. Many designs pour them as one monolithic shape, which this calculator's plain cylinder geometry doesn't fully capture — check your specific detail.
• –Skipping a form above grade because a post hole didn't need one. Below grade, soil holds concrete's shape; above grade, wet concrete has nothing to push against without a form.
• –Using an unbraced or out-of-plumb tube form. Wet concrete is heavy enough to bulge, lean, or split a form that isn't set straight and supported.
• –Running the calculator once per pier instead of using the quantity field for identical piers — small rounding differences add up across a full row.

Where the density figure comes from

Unlike the landscape materials on this site, concrete is a manufactured product with a tightly controlled mix, so its density varies far less than gravel, sand, or mulch — and the same figure applies whether it's poured as a slab, a footing, or any other normal-weight element. CEMEX, a major ready-mix producer, puts a solid unbroken pour at about two tons (4,000 lbs) per cubic yard. ACI 318 and ASTM C138 define normal-weight concrete at 145–150 lb/ft³ — ACI 318 uses 150 lb/ft³ as its default structural value — which works out to 3,915–4,050 lbs (1.96–2.03 tons) per cubic yard. The 1.95–2.03 ton/yd³ range here reflects that normal-weight span, not moisture variation. Lightweight and heavyweight concrete mixes fall outside this range and aren't covered by this calculator. We use 2.02 tons/yd³ as the display figure, drawn from:

• CEMEX — Ready-Mix Concrete Calculator
• ACI 318 & ASTM C138 — normal-weight concrete density, 145–150 lb/ft³

Read more in our density methodology.

FAQ

How wide or tall should a pier or column be?

It depends on the structural load it carries, your soil's bearing capacity, and your local frost depth — your local building department or the International Residential Code sizes that for your specific situation. There's no universal number here; this calculator only converts whatever diameter and height you enter into a volume.

What's the difference between a pier and a footing?

A footing is the buried base that spreads a structure's load into the soil — wide and shallow. A pier is the vertical column that carries load from a post or beam down to that footing. Many designs pour both as one monolithic shape; check your specific detail before assuming this calculator's plain cylinder covers the whole pour.

Why doesn't this calculator subtract anything, like the post hole calculator does?

Because a column or pier is a solid pour, not a ring around a post. The post hole calculator subtracts the post's own footprint from the hole because concrete only fills the gap around it; a pier or column is poured as one continuous solid cylinder, so the full volume is what you need.

Do I need a cardboard tube form?

Above grade, yes — wet concrete has nothing to hold its shape against without one, and a tube form (often sold under the brand name Sonotube) is the standard choice for a round column or pier. Below grade, surrounding soil can act as the form the way it does for a post hole, though many pours still form the full height for a cleaner, more consistent column.

Can I calculate concrete for multiple piers at once?

Yes — enter the quantity of identical piers in the Quantity field and the calculator multiplies the per-pier volume automatically. This only works for piers that are all the same diameter and height; calculate different sizes separately and add the results together.

Should I use bags or ready-mix for columns and piers?

It depends on scope. A handful of deck piers are usually small enough that bags make sense on their own. A longer row, or taller porch columns, adds up fast — past roughly half a cubic yard total, ready-mix delivery is generally cheaper and far less labor than mixing bag after bag by hand.

Why does concrete's weight vary so little compared to gravel or sand?

Concrete is a manufactured product with a tightly controlled mix ratio, so its density is far more consistent than a quarried or organic material's. The range on this site comes from ACI 318 and ASTM C138's normal-weight concrete specification (145–150 lb/ft³), the same figures used for the slab, footing, and post hole calculators, not from moisture swings the way gravel, sand, or mulch vary.