Footing & Pier Takeoff
Strip footing and pier concrete in cubic yards, tube forms, rebar footage, gravel base, and forms, sized to the frost depth you dig to.
Frost depth drives the footing, not the plan: a footing must bear below the frost line in most of the country, and the porch footing often ties to the main at a stepped section.
How the math works
- Volume: strip = length × (width ÷ 12) × (depth ÷ 12) cubic feet, ×1.05 for over-excavation and spread. Pier = π × (d÷2)² × depth. 27 cu ft = 1 cubic yard.
- Bags: an 80 lb bag yields 0.63 cu ft, so bags = cu ft ÷ 0.63. A 5 yard mixer truck is 27 cu yd = 112 bags, which is why footings over 2 yards are a ready-mix job.
- Rebar: two continuous #4 bars in the strip at 48 in lap splices (one splice per 20 ft), and 2 to 4 bars in each pier run out into the footing with the lap. #4 = 0.668 lb per ft, #3 = 0.376, #5 = 1.043.
- Tube forms: sonotube ships in 24 in lengths; tubes = piers × depth ÷ 2, and the pier head is stubbed into the footing with 4 in of cover. A 12 in tube takes 4.7 cu ft per foot of depth.
- Gravel base: 4 in of clean 3/4 crush under the footing = 0.15 tons per sq ft of footprint. Compacted base at 1.15 tons per cubic yard; the 2026 delivered price is $85 to $125 per ton.
How deep do footings need to be?
Below the frost line in every frost jurisdiction: 30 to 48 in across the northern states, 12 to 18 in in the warm southeast, and deep frost in the upper midwest. Check your county frost depth, not your neighbor’s habit.
How many cubic yards for a 60 foot footing?
A 12 in wide, 18 in deep footing runs 90 cu ft of strip plus the 5% overdig, 94 cu ft, which is 3.5 cubic yards: about 7,100 lb of concrete, one small ready-mix load.
How much rebar goes in a footing?
Two continuous #4 bars 3 in from the bottom and sides, one splice per 20 ft with a 48 in lap, and 2 bars per pier run down into the tube. A 60 ft run with 8 piers is about 170 ft of #4, 114 lb.