Input-to-output map for this calculator
| Displayed output | Height-only edit? | Other inputs used |
|---|---|---|
| Rails | Yes | Net run, gate count and width, post spacing |
| Post-length / embedment notes | Yes | Selected height unit |
| Posts | No | Net run, post spacing and gate count |
| Wood pickets / slats | No | Net run, board width and gap |
| Wood fastener allowance | Yes, through rails per section | Picket count and rails per section |
A controlled comparison
Using a 100 ft run, 8 ft post spacing, no gates, 5.5 in picket width, and a 0 in gap, the actual handler returns 14 posts and 219 pickets at either a 6 ft or 8 ft height. The rail calculation changes from 39 to 52 because the code assigns three versus four rails per straight-run section. Its wood fastener allowance changes from 1,314 to 1,752 with that rail multiplier. The formula notes show a 9 ft versus 12 ft estimated post length and a 3 ft versus 4 ft one-third figure.
Those are outputs of the current software formulas for these entered values, not a material specification or a recommendation about how a fence should be built. Use the chosen system's documentation and the actual project requirements for design decisions.
Why some cards stay the same
The post equation is based on sections after gate deductions, plus endpoint and gate allowances. The wood infill equation uses net run divided by board width plus gap. Neither expression includes height. Rails do: the calculator divides height in inches by 24, rounds up, and multiplies that per-section amount by straight-run sections. Its fastener branch then uses pickets and rails per section.
A height change can therefore alter some totals without changing the fence length or number of posts. If a result looks unchanged, submit the form again and check which output is expected to depend on the edited input.
Source and limits
This comparison follows the current form labels and calculation code. The example was tested against the actual submit handler. It covers one straight-run estimate and does not calculate a multi-side layout, verify product compatibility, or establish construction requirements.
Read how rail quantities are calculated for that formula, or how to interpret the post-length note for its limits.