Fence Calculator
Estimate posts, pickets and rails for a straight fence.
Loading calculator…
What this tool does
Estimate posts, pickets and rails for a straight fence. Includes both end posts; gates and corners require separate adjustments.
How to use the Fence Calculator
- Enter or select fence length in ft.
- Enter or select maximum post spacing in ft.
- Enter or select fence height in ft.
- Enter or select actual picket width in in.
- Enter or select picket gap in in.
- Enter or select rails per bay.
- Enter or select waste allowance (%).
- Read the calculated result; change any measurement to compare alternatives.
Formula
bays=ceil(length/span); posts=bays+1; pickets=ceil(length×12/(picket+gap)×(1+waste/100)); rails=bays×railsPerBay
- length
- Fence length (ft, before metric conversion)
- span
- Maximum post spacing (ft, before metric conversion)
- height
- Fence height (ft, before metric conversion)
- picket
- Actual picket width (in, before metric conversion)
- gap
- Picket gap (in, before metric conversion)
- rails
- Rails per bay
- waste
- Waste allowance (%)
Includes both end posts; gates and corners require separate adjustments.
Worked example
For fence calculator, the following measurements illustrate the exact method: Fence length: 100; Maximum post spacing: 8; Fence height: 6; Actual picket width: 5.5; Picket gap: 0.5; Rails per bay: 3; Waste allowance (%): 10.
Inputs
- Fence length100 ft
- Maximum post spacing8 ft
- Fence height6 ft
- Actual picket width5.5 in
- Picket gap0.5 in
- Rails per bay3
- Waste allowance (%)10
Result
- Posts14
- Pickets221
- Rails39
- Equal bay spacing7.69 ft
Results explained
- Posts
- Posts from the formula above. Includes both end posts; gates and corners require separate adjustments.
- Pickets
- Pickets from the formula above. Includes both end posts; gates and corners require separate adjustments.
- Rails
- Rails from the formula above. Includes both end posts; gates and corners require separate adjustments.
- Equal bay spacing
- Equal bay spacing from the formula above, expressed in ft before metric conversion. Includes both end posts; gates and corners require separate adjustments.
Frequently asked questions
Round bays up by maximum post spacing, add one end post, and count pickets by coverage width.
Measure fence length, desired post spacing and actual picket width/gap.
Use 5–10% for simple layouts and 10–15% for diagonal cuts or complicated outlines; the allowance is editable.
Split the outline into rectangles or triangles and calculate each section separately. Do not count overlapping sections twice.
This is a purchasing estimate, not a structural design. Confirm measurements and local requirements before buying or building.