PICKETPILOT FIELD GUIDE
Estimate concrete bags from hole geometry
Hole depth is not always concrete depth, and bag weight is not volume. Keep both distinctions explicit when estimating the order.
Subtract the space occupied by the post
For a round hole with a rectangular post, net volume in cubic feet is [π × (diameter ÷ 2)² − post width × post depth] × concrete fill height ÷ 1,728. All dimensions in that formula are inches. Use actual post dimensions.
Concrete fill height is only the height occupied by concrete. Do not automatically use total excavation depth if the chosen installation includes a different base or top treatment. This calculator does not select a foundation or specify hole dimensions.
Convert volume using the exact product yield
QUIKRETE Fast-Setting Concrete Mix’s product sheet lists approximately 0.375 cubic feet for a 50-pound bag and 0.45 cubic feet for a 60-pound bag. Select the yield from your exact product, because equal-weight bags of different products need not cover the same volume.
As an arithmetic example only, a 12-inch-diameter hole, 3.5-by-3.5-inch post and 24 inches of concrete fill uses about 1.401 cubic feet before extra allowance. At 0.375 cubic feet per bag, one such hole rounds to four bags. These dimensions are not a foundation recommendation.
Choose the rounding method
Pooled rounding totals all holes before rounding bags. Per-hole rounding allocates whole bags to each hole and can produce a higher purchase count. An editable extra percentage applies before rounding; it does not resolve unsuitable dimensions or installation requirements.
The worksheet supports identical holes only. Calculate differing line and gate foundations separately and reconcile the combined order. Confirm installation details with the product instructions and a qualified local source. Before any digging, use the official 811 planning guidance for your location.