How to use this calculator
- Enter every fence run receiving pickets.
- Enter the actual picket face width.
- Enter the planned clear gap between pickets.
- Set waste and calculate whole pickets.
How the calculation works
Picket width and clear gap form a repeating module. Total run length is divided by that module, rounded up, then waste is applied and the purchase result is rounded up again.
Formula
Picket module = picket width + gap Base pickets = ceil(total run length ÷ module) Purchase pickets = ceil(base pickets × (1 + waste %))
Worked example
A 40 ft fence is 480 inches. With 5.5 in pickets and 0.5 in gaps, the 6 in module requires 80 pickets. At 10% waste, plan for 88 pickets.
Project considerations
- Actual face width may differ from nominal lumber dimensions.
- The simple repeating-module estimate does not optimize end gaps or model posts and gates.
- Verify the intended gap, product dimensions, and layout before purchasing.
Frequently asked questions
Is the last gap counted exactly?
No. This is a practical repeating-module estimate and rounds upward rather than promising an exact end-gap layout.
Can the gap be zero?
Yes. A zero gap is accepted, while picket width must remain greater than zero.