Fence Post Concrete Calculator
Estimate how much concrete is needed for round fence post holes and see approximate 40 lb, 60 lb and 80 lb bag counts.
Post hole details
Estimate
This estimate treats the hole and post as round cylinders. A square post entered as its width is only an approximation; field hole shapes also vary.
How fence post concrete is calculated
The concrete occupies the space in the post hole that is not occupied by the post. The calculator finds the cylindrical hole volume, subtracts the approximate post volume, multiplies by the number of holes and adds waste.
Measure the actual hole
Augered holes can widen or become irregular below grade. Measure representative holes when possible and use a reasonable allowance rather than relying only on the nominal auger diameter.
Fence post concrete FAQ
Does every fence post need concrete?
Installation methods depend on fence type, soil, climate and local practice. Follow the fence system instructions and applicable local requirements.
Why subtract the post volume?
The post itself occupies part of the hole, so subtracting it gives a closer estimate of the space filled by concrete.
Can I calculate gate posts too?
Yes, but if gate posts use larger holes, calculate those separately using their actual dimensions.