Concrete Column & Pier Calculator
Pick round or rectangular, enter the size and height, say how many you are pouring, and get the concrete to order in cubic yards, the bag count, the weight and an optional cost. A round column is sized by the inside diameter of the form tube, which is the size the tube is sold by.
Concrete to order
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Results are estimates for planning purposes. Verify with your supplier, engineer, or a qualified professional before ordering material or performing work.
Round columns: concrete per linear foot, by diameter
| Diameter | ft³ per foot | 80 lb bags per foot | Linear feet per yd³ | Weight per foot |
|---|---|---|---|---|
| 6 in | 0.196 | 0.33 | 137.5 | 28 lb |
| 8 in | 0.349 | 0.58 | 77.3 | 51 lb |
| 10 in | 0.545 | 0.91 | 49.5 | 79 lb |
| 12 in | 0.785 | 1.31 | 34.4 | 114 lb |
| 14 in | 1.069 | 1.78 | 25.3 | 155 lb |
| 16 in | 1.396 | 2.33 | 19.3 | 202 lb |
| 18 in | 1.767 | 2.95 | 15.3 | 256 lb |
| 20 in | 2.182 | 3.64 | 12.4 | 316 lb |
| 24 in | 3.142 | 5.24 | 8.6 | 456 lb |
| 30 in | 4.909 | 8.18 | 5.5 | 712 lb |
| 36 in | 7.069 | 11.78 | 3.8 | 1,025 lb |
Arithmetic from π/4 × diameter², before any waste allowance. Bag counts use the 0.60 ft³ yield of an 80 lb bag of QUIKRETE Concrete Mix; weight uses 145 lb/ft³. Form tubes are sold by inside diameter, so the tube size and the column size are the same number.
Pouring columns and piers
- Diameter costs more than height. Volume goes with the square of the diameter: going from a 10 in tube to a 12 in tube is 20% more diameter and 44% more concrete. Going from 4 ft to 5 ft of height is 25% more concrete. Check the plan before you buy the bigger tube.
- A drilled pier is rarely a clean cylinder. Augered holes slough, and a belled bottom holds more than the shaft calculation shows. A 10% allowance covers a tidy hole in firm ground; loose or wet ground can take considerably more.
- Brace the form before you pour. Fresh concrete pushes hard on a tall tube — a 12 in column 8 ft tall is over 900 lb of wet concrete sitting on the form and its bracing.
- Pier plus footing is two shapes. Work out the pad in the footing calculator, the shaft here, and add the two.
- Not a structural design. Diameter, depth, reinforcement and bearing come from the engineer. This page converts the dimensions you were given into a concrete order.
How it's calculated
- Round column
V (ft³) = π / 4 × (diameter (in) / 12)² × height (ft)A 12 in tube holds 0.785 ft³ per linear foot, so 34.4 linear feet make a cubic yard.- Rectangular column
V (ft³) = side A (in) / 12 × side B (in) / 12 × height (ft)- Total volume
V total = V × number of columns → yd³ = ft³ / 27- Volume to order
V order = V total × (1 + waste % / 100)ASTM C94, quoted in NRMCA TIP 8, lists the reasons the placed volume exceeds the calculated one. On drilled piers the bottom of the hole is the usual culprit.- Weight
weight (lb) = V total (ft³) × 145 lb/ft³Normalweight concrete runs 140 to 150 lb/ft³ (NRMCA CIP 36); 145 is the midpoint used here.- Bags
bags = ceiling(V order (ft³) / yield per bag), yield = 0.30 ft³ (40 lb), 0.45 ft³ (60 lb), 0.60 ft³ (80 lb)Published yields for QUIKRETE Concrete Mix No. 1101. Check the bag you buy — yield varies by product.
Frequently asked questions
0.785 cubic feet per linear foot, which is 1.31 bags of 80 lb mix. A cubic yard fills 34.4 linear feet of 12 in tube. An 8 in tube holds 0.349 ft³ per foot and a 10 in tube 0.545 ft³ per foot.
3.14 cubic feet each, 18.85 cubic feet for six, which is 0.70 cubic yards. With a 10% allowance you would order about 0.77 cubic yards, or buy 35 bags of 80 lb mix.
The inside diameter, which is the size the tube is sold by. A 12 in form tube pours a 12 in column; the wall thickness of the cardboard is not concrete and is not part of the volume.
No. A pier that sits on a spread footing or a belled bottom is two pours with two shapes. Run the pier here and the footing in the footing calculator, then add them. If the hole is belled at the bottom, add a few percent to the waste allowance rather than trying to model the bell.
About 145 lb per cubic foot, so a 12 in column weighs roughly 114 lb per linear foot and a 24 in pier about 455 lb per linear foot. Normalweight concrete ranges from 140 to 150 lb/ft³ according to NRMCA CIP 36.
Yes, in substance. Sonotube is a brand of cardboard form tube; the volume of a round column depends only on its diameter and height, not on who made the form. Enter the tube's nominal diameter and you get the same number.
Small piers are routinely bagged. Six 12 in piers 4 ft deep is 35 bags of 80 lb, about 2,800 lb of mix, which is a long afternoon with a mixer. Past a cubic yard or so, most crews price a short-load delivery instead.
No. Diameter, depth, reinforcement and the bearing the pier needs come from the engineer or the plan. This calculator converts the dimensions you already have into a concrete order.
Sources & references
- QUIKRETE Concrete Mix No. 1101 — product data sheet (yield per bag: 0.30 ft³ at 40 lb, 0.45 ft³ at 60 lb, 0.60 ft³ at 80 lb)
- NRMCA CIP 36 — Structural Lightweight Concrete (normalweight density 140–150 lb/ft³)
- NRMCA TIP 8 — Concrete Yield: why the placed volume exceeds the calculated volume, per ASTM C94
Content checked against these sources — last reviewed August 28, 2026.