Measuring the net fence length
Measure the length of fence material needed for one straight continuous run. Subtract gates, driveway openings, walkways, and other unfilled openings before entering the value.
Outdoor calculator
Fence Calculator
Calculate fence pickets, panels, posts, and rails for one straight continuous fence run, including material dimensions, spacing, gaps, waste allowance, and optional primary material cost with US, metric, or mixed units.
How many fence pickets or panels do you need for a straight run?
Pickets, panels, posts, rails, and cost
Project inputs
Enter dimensions
Estimate
Pickets to buy
Planning purchase quantity
221pickets
5.5 in picket width · gap 0.5 in · waste 10%
Rounded up to whole pickets for one straight fence run—not a layout or structural takeoff.
Breakdown
Fence length100 ft
Maximum post spacing8 ft
Exact section count12.5
Sections required13
Actual average section length7.69 ft
Posts required14
Rails per section2
Rails required26
Picket width5.5 in
Gap between pickets0.5 in
Exact pickets before waste200.08
Waste allowance10%
Waste pickets20.01
Exact pickets with waste220.09
Pickets to buy221
Picket rounding overage0.91
Purchased physical picket width101.29 ft
Estimated picket cost
Enter a price per picket to estimate material cost.
How it's calculated
Sections = ceil(fence length ÷ maximum post spacing) · Posts = sections + 1 · Rails = sections × rails per section · Exact pickets = (fence length + gap) ÷ (picket width + gap) · Pickets to buy = ceil(exact pickets × (1 + waste percentage))
- Fence length is treated as one straight continuous run.
- Length is divided by maximum post spacing.
- Sections are rounded up to the next whole section.
- One post is added relative to section count for a straight run.
- Rails are calculated for each section.
- Pickets are calculated from actual width and gap.
- Waste is applied to the exact picket count.
- The result is rounded up to whole pickets.
- Cost uses pickets to buy when price is entered.
Method
How to calculate fence materials
Measure the net fence length for one straight run, subtract gates and openings, choose individual pickets or prefabricated panels, enter actual material dimensions and spacing, add waste allowance, and review pickets or panels to buy plus optional material cost.
Subtracting gates and openings before calculation
This calculator has no openings field. Gate widths and other gaps must be removed from your measured length before you enter fence length.
Calculating separate fence runs separately
Each straight run with different lengths, corners, or conditions should be calculated individually. This tool handles one continuous straight run per calculation.
Choosing between individual pickets and panels
Individual pickets mode estimates pickets, posts, and rails for spaced or privacy picket fences. Prefabricated panels mode estimates panels and posts for pre-built panel sections.
Using actual material dimensions
Enter actual picket or panel width from your product specification. Nominal lumber names and advertised sizes often differ from finished dimensions.
Choosing post spacing
Maximum post spacing is a planning divisor. Sections round up, so actual average spacing may be less than your entered maximum. Confirm spacing with manufacturer and local requirements separately.
Calculating sections and posts
Fence length divided by maximum post spacing gives exact sections. Sections round up. Posts for one straight run equal sections plus one.
Calculating rails
Rails required equal sections multiplied by rails per section. Rail length, cuts, and waste are not optimized—this is a count of rail pieces by section.
Accounting for picket gaps
Gap between pickets affects how many pickets fit along the run. Zero gap is valid. The trailing gap after the last picket is not required.
Calculating panels
Fence length divided by panel width gives exact panels. Layout quantity rounds up to full panel positions. Posts follow layout positions, not spare panels purchased for waste.
Why the last panel may require trimming
When fence length is not a multiple of panel width, the last installed panel may need cutting. Layout overage is not automatically reusable leftover material.
Choosing waste allowance
Waste applies only to pickets or panels—not posts or rails. Account for cuts, defects, and trimming in your chosen percentage.
Exact quantities versus quantities to buy
Exact quantities are mathematical values before rounding. Quantities to buy round up after waste is applied. Partial pickets or panels cannot be purchased.
Why corners and gates require separate planning
Corner posts, gate posts, brace posts, and terminal assemblies are not included. Plan those additions outside this calculator.
What material cost includes and excludes
Cost covers pickets or panels to buy when price is entered. Posts, rails, gates, hardware, concrete, delivery, labor, and taxes are excluded.
Post depth, concrete, and structural requirements
Post depth, hole volume, footings, concrete, gravel, wind loads, frost depth, and code compliance require separate planning tools and professional guidance.
Common questions
Fence calculator FAQ
How do I calculate how many fence pickets I need?
Measure the net length of one straight fence run after subtracting gates and openings, enter maximum post spacing, rails per section, actual picket width, gap between pickets, and waste allowance, then press Calculate. The calculator determines sections, posts, rails, exact pickets before waste, and pickets to buy rounded up to whole pickets.
How do I calculate how many fence panels I need?
Enter the net fence length for one straight run, the actual width of your prefabricated panel, and waste allowance, then press Calculate. The calculator determines panels required for layout, posts, installed panel capacity, layout overage, and panels to buy with waste rounded up.
How many fence posts do I need?
For one straight continuous run, posts equal sections or panel positions plus one—a post at each end and between each section or panel. This calculator does not add corner posts, gate posts, brace posts, or terminal assemblies. Calculate those separately for your layout.
What post spacing should I use for a fence?
Post spacing depends on fence material, height, construction, wind loads, manufacturer requirements, and local codes. This calculator uses your entered maximum spacing as a planning divisor—it does not prescribe one universal spacing. Actual average spacing may be less than your maximum when sections are rounded up.
Should I use the actual or nominal width of a picket or panel?
Use the actual face width from your product specification—not the nominal lumber name or advertised size. A nominal 6-inch picket often measures about 5.5 inches. Panel nominal sizes may differ from installed width. Using nominal size overestimates coverage and underestimates material quantity.
How does the gap between pickets affect the calculation?
Gap is added to picket width to determine how many pickets fit along the fence length. A larger gap means fewer pickets. Zero gap means no planned spacing between pickets. The trailing gap after the last picket is not counted as required spacing.
Should I subtract gates and openings from the fence length?
Yes. Enter the net length that must be filled with fence material after subtracting gates, driveway openings, walkways, and other unfilled openings. This calculator does not have a separate openings field—subtract those widths before entering fence length.
How much extra fence material should I allow for waste?
Waste depends on cuts, damaged pieces, measurement errors, defects, end trimming, and layout complexity. A 10% allowance is a common planning starting point, but requirements vary by project. Enter the percentage that fits your job—the calculator does not prescribe one universal value.
Why might the last fence panel need to be cut?
When fence length is not an exact multiple of panel width, the last installed panel position may require trimming or a narrower custom section. Layout quantity rounds up to cover the full length. Layout length overage is not guaranteed reusable leftover material.
Does the estimated cost include posts, rails, concrete, gates, delivery, and labor?
No. Individual pickets mode estimates cost from pickets to buy only. Prefabricated panels mode estimates cost from panels to buy only. Posts, rails, gates, gate hardware, fasteners, brackets, caps, concrete, gravel, stain, paint, tools, delivery, labor, permits, and taxes are excluded.
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