Compare total length with all gate openings
Start with the full length of the single run, including its gate openings. In this tool, gate count is multiplied by one common gate width. The calculator converts the total length to feet, but the gate-width field remains in feet even if you select metres or another unit for total length.
Let L be total length in feet, G the whole-number gate count, and W the common gate width in feet. The actual calculation is:
remaining run = max(0, L − G × W)
The max operation prevents a negative quantity from entering the material formulas. It does not reject an oversized set of openings, locate the gates, or tell you that their positions work. When G × W is greater than L, first recheck the measurement, selected length unit and gate-width unit.
Three hypothetical input checks
These original examples were executed against this site's submit handler. They are software boundary checks, not recommended fence or gate dimensions. Each uses a 10 ft total run, 6 ft height, 8 ft post spacing, one gate, and wood infill with 5.5 in width and zero gap.
| Gate width | Remaining-run calculation | Posts | Rails | Pickets |
|---|---|---|---|---|
| 4 ft | max(0, 10 − 4) = 6 ft | 4 | 3 | 14 |
| 10 ft | max(0, 10 − 10) = 0 ft | 3 | 0 | 0 |
| 12 ft | max(0, 10 − 12) = 0 ft | 3 | 0 | 0 |
The last two inputs give identical material cards although one opening equals the measured run and the other exceeds it. This is why a plausible-looking post count cannot validate the geometry. Inspect the entered values as well as the result.
Why posts remain when infill disappears
The tool first rounds up remaining run ÷ post spacing to get straight-run sections. Its post count is sections + 1 + 2 × gate count. With zero remaining run and one gate, this evaluates to 0 + 1 + 2 = 3 posts. With two gates it evaluates to 0 + 1 + 4 = 5 posts.
The endpoint term does not disappear when the run reaches zero. This explains the displayed result; it does not mean a gate-only layout actually needs those quantities. This estimator has no position-by-position post model, shared-post logic or gate-leaf takeoff.
Other cards can still contain quantities
Zero straight-run sections produce zero rails. Wood fasteners also become zero because this branch multiplies the picket count by the height-based rail count and two connections. The chain-link planning allowance is different: sections × 4 + gates × 4. One gate and zero sections therefore still produce four fasteners in that branch, alongside 0.0 ft of fabric.
Concrete follows the post count, not the infill length. If you supply a positive per-post concrete volume, the tool can show concrete even when pickets are zero. In a controlled example with three calculated posts, a hypothetical 1 ft³ per post gives 3 × 1 = 3 ft³; a hypothetical 0.5 ft³ bag yield gives ceil(3 ÷ 0.5) = 6 bags. These inputs are test values, not product yields or hole-size advice.
A short correction checklist
- Check that total length describes this one complete run, not only the solid infill portion before gate subtraction.
- Check the total-length unit; keep gate width and post spacing in their labelled feet units.
- Multiply the whole-number gate count by the common gate width yourself and compare it with total length.
- If gate widths differ, do not treat the one-width field as a gate-by-gate layout tool.
- After correcting inputs, press Calculate materials again before relying on or copying the result.
The equality case is not automatically a measuring error, but it is outside what this infill-planning formula can resolve into a detailed gate-only design. Plan the actual supports and gate system separately.
For an ordinary positive run, see how gate openings are deducted. For field units, see the measurement-input guide. All results retain the single-run scope limits.
Method and test source
This guide documents this site's calculation code, including its zero floor, section rounding, post terms and fence-type branches. Independent handler checks covered positive, equal and oversized openings, two gates, chain-link output and concrete quantities. They check arithmetic with supplied inputs; they do not simulate a build, certify a safe layout, or replace a site measurement.