The short answer
For each straight, solid fence segment, divide its length by the space covered by one picket and round up. Add the segment counts, then apply your waste allowance. Measure gate openings separately: do not count pickets across an opening.
Base pickets per segment = ceil((length in ft × 12 + gap in in) ÷ (actual picket width in in + gap in in))
Quantity to buy = ceil(total base pickets × (1 + waste % ÷ 100))
Use inches for both picket width and gap. The formula treats each solid segment separately, rounds each segment up, sums those base counts, and only then applies waste.
What do width and gap mean?
Use the picket’s actual face width for your chosen product, not a nominal size copied from a different board. The gap is the clear space between neighboring pickets. In this guide, 5.5 in is an example input, not a claim about every product sold under a particular nominal label.
Picket count examples
These examples use an assumed actual width of 5.5 in and show one continuous solid segment. The 10% allowance is illustrative; choose an allowance that reflects your cuts, layout, and selected material.
On a narrow screen, scroll the table horizontally to see both gap options and the quantities with waste.
| Fence length | 0 in gap base | 0 in gap with 10% waste | 0.25 in gap base | 0.25 in gap with 10% waste |
|---|---|---|---|---|
| 50 ft | 110 | 121 | 105 | 116 |
| 100 ft | 219 | 241 | 209 | 230 |
| 150 ft | 328 | 361 | 314 | 346 |
| 200 ft | 437 | 481 | 418 | 460 |
Counts are rounded up. “With 10% waste” means ceil(base count × 1.10); it is not a guarantee that every project’s offcuts or damaged boards will be covered.
Worked example: 100 ft of fence
Assume one solid 100 ft segment, 5.5 in actual picket width, no gap, and a 10% waste allowance:
- Convert the length:
100 × 12 = 1,200 in. - Calculate the base count:
ceil(1,200 ÷ 5.5) = ceil(218.18…) = 219 pickets. - Apply the allowance:
ceil(219 × 1.10) = ceil(240.9) = 241 pickets to buy.
With the same length and width but a 0.25 in gap, the base count is ceil((1,200 + 0.25) ÷ (5.5 + 0.25)) = 209; with 10% waste, that becomes ceil(209 × 1.10) = 230.
The wood fence cost calculator uses the same 100 ft, 5.5 in, zero-gap, 10% example: 219 base boards and 241 to buy.
Gates, corners, and multiple segments
Subtract gate openings from the solid fence length. Calculate each solid segment on its own because a new segment starts a new board layout; add the rounded base counts, then apply waste once to the combined total. Do not count boards across a gate opening.
For example, a 20 ft run with a 4 ft gate and 8 ft of solid fence on each side has two segments to calculate. At 5.5 in width and no gap, each 8 ft segment needs ceil((8 × 12) ÷ 5.5) = 18 base pickets, for 36 base pickets total. With 10% waste, that is ceil(36 × 1.10) = 40.
For connected runs, calculate the solid lengths on either side of gates and corners according to your layout. This quantity estimate does not decide board placement at corner posts, the fence style, or a construction detail.
What this estimate does not include
The calculation does not optimize cutoffs, account for picket shape or overlap, or determine whether a particular layout meets local rules or installation requirements. Confirm product dimensions and layout before ordering. It is a material planning estimate, not a cut list, structural design, or professional approval.
Review the full calculator methodology and model limits, then use the wood fence calculator with your own dimensions.