Post hole formula
A post hole is estimated as a cylinder: pi times radius squared times depth. Diameter is entered in inches and depth can use feet and inches.
Multiply by the number of holes, then add waste and round the bag count up.
Posts and footings
Post Hole Concrete Calculator
Estimate concrete for fence posts, deck footings and round holes.
US units
10% default waste
Bag and yard estimates
Concrete estimate
Enter dimensions
Estimate assumptions
- Estimates are for planning and ordering only.
- Bag counts are rounded up to whole bags.
- Ready-mix yards are rounded up to the nearest 0.25 cubic yard.
- Default waste is 10%. Increase it for uneven excavation, spillage, or complex forms.
- Verify structural work with a contractor, engineer, or supplier before pouring.
Post hole reminders
- DiameterMeasure the hole diameter, not the post width.
- DepthFollow local frost-depth and structural guidance where required.
- QuantityUse the number of holes with the same diameter and depth.
Common next purchases
Concrete mix
Rebar
Tube forms
Mixing tools
Trowels and floats
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FAQ
How much concrete per fence post?
It depends on hole diameter and depth. Enter both dimensions and the number of posts to get a bag estimate.
Can I use this for deck footings?
Yes for a volume estimate, but deck footings may require code-specific sizing.
Should I include gravel at the bottom?
This calculator estimates concrete only. Any gravel base should be estimated separately.