Cubic feet
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Post Hole Concrete Calculator
Post Hole Concrete calculator
Calculate concrete for fence-post and deck-footing holes. Cubic yards, bags, ready-mix loads and weight — with a waste margin built in, nothing leaves your browser.
Dimensions
FIG. 01Volume ÷ 27 = cubic yards. Pros order to the nearest ½ yard and add a waste margin — running short mid-pour risks a cold joint.
You need
—cu yd
Order to nearest ½ yd → — · —
Cubic meters
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80 lb bags
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60 lb bags
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Est. weight
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Best buy
see above
How this is calculated
Each hole is π × radius² × depth. An 8-inch hole 3 ft deep holds about 1.05 cubic feet — roughly two 80-lb bags. Fast-setting concrete is popular here because posts can be set in 20–40 minutes.
cubic yards = volume in cubic feet ÷ 27 × (1 + waste%)
For the full method and sources, see the methodology page. Comparing buying options? Use the bags-vs-ready-mix calculator.
FAQ
How much concrete per post hole?
Each hole is π × radius² × depth. An 8-inch hole 3 ft deep holds about 1.05 cubic feet — roughly two 80-lb bags. Fast-setting concrete is popular here because posts can be set in 20–40 minutes.
How many bags of concrete per fence post?
For an 8-inch hole 2–3 ft deep, plan on 1–2 bags of 80 lb fast-setting mix per post. Multiply by your post count — this calculator does it when you set the number of holes.