Cubic feet
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Project guide
Concrete for Fence Posts?
How much concrete for fence post holes — hole sizing, bags per post, and a calculator for any number of posts.
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
Sizing it right
Setting fence posts is a bag job, not a truck job — but it's easy to under-buy because the per-hole volume is small and the post count is high.
Size the hole right
A common rule: the hole is about three times the post width and a third of the post's above-ground height deep, below the frost line. For a standard wood fence post that's often an 8–10 inch diameter hole, 2–3 feet deep.
Bags per post
An 8-inch hole 2.5 feet deep holds roughly 0.9 cubic feet — about 1.5 to 2 bags of 80 lb concrete per post (fast-setting mix is popular here, since posts can set in under an hour). Multiply by your post count. The calculator below does exactly this — set the number of holes.
Account for the post itself
The post displaces some concrete, so real usage is slightly lower than the bare hole volume — buying to the full hole volume gives a safe margin. For deck footings rather than fence posts, the column and bell pier calculators fit better.
FAQ
How much concrete per fence post?
For an 8-inch hole 2–3 feet deep, plan on 1.5–2 bags of 80 lb concrete per post. Enter your hole size and post count above for the total bags and yardage.
How deep should fence post holes be?
Roughly a third of the post's above-ground height, and always below your local frost line — commonly 2–3 feet for a residential fence. Deeper, wider holes hold better in loose or frost-prone soil.