Lay out the fence before counting posts
The calculator describes one straight run with a post at each end. Gates, corners, changes in height and connections to existing structures need their own layout. Confirm property boundaries, service locations and local requirements before planning excavation.
How spacing changes a 100-foot run
| Maximum bay length | Bays, rounded up | Posts for one run |
|---|---|---|
| 8 ft | 100 ÷ 8 → 13 | 14 |
| 6 ft | 100 ÷ 6 → 17 | 18 |
These are counting examples, not a panel layout. The last bay will be shorter if full bays are used first. Check the panel manufacturer's actual dimensions and attachment details before setting post positions.
A 48-foot worked example
At an 8-foot bay length, a 48-foot run has six bays and seven posts. The tool's illustrative hole model uses a 10.5-inch diameter and a depth of one-third of an 8-foot post. That gross cylinder is approximately 1.604 cubic feet per hole. With 0.60 cubic feet per 80-pound bag and rounding per hole, it gives three bags per hole, or 21 bags.
The gross-hole model does not subtract the post's displacement. It also does not determine the required depth for frost, soil, wind or fence height. Obtain those dimensions for your site and confirm the concrete product and installation method.
Why rounding per hole changes the order
Seven gross holes total about 11.23 cubic feet. Dividing that combined volume by 0.60 and rounding once gives 19 bags; rounding each separate hole up gives 21. The calculator uses the latter planning approach. Material that can be shared between holes may reduce leftover mix, but working time and installation instructions still apply.
Price the missing parts
Include panels or pickets, rails, posts, concrete, caps, fasteners, gates and hardware, delivery and disposal. The displayed subtotal excludes any line without a price. A gate opening is not simply another standard panel.