How this calculator works
First we subtract the gates from the run. The remainder is divided by your post spacing, rounded up, to get the number of sections. A straight fence needs one more post than sections, plus an extra post for each gate. Rails are counted per section (two for a 4 ft fence, three for taller ones), and boards are counted across the run using the width of each picket plus any gap.
Worked example: 100 ft of 6 ft fence with one 4 ft gate and 8 ft spacing: the run is 96 ft, so 12 sections and 14 posts. With 1×6 pickets set tight (5.5 in), you need 96 × 12 ÷ 5.5 = 210 pickets, plus 36 rails. At 24 in deep, the post holes take about 24 bags of 80 lb concrete.
Tips before you buy
- Use pressure-treated posts rated for ground contact. Pickets and rails can be cedar, redwood or treated pine.
- Plan on burying about one third of the fence height, with a minimum of 2 ft: a 6 ft fence takes 8 ft posts set about 2 ft deep, and an 8 ft fence takes 11 to 12 ft posts set about 3 ft deep. Go deeper where soil freezes. Check local code, since many places require a permit or set maximum fence heights.
- Check where your property line is before you dig, and call 811 (in the US) to have buried utilities marked.
- Buy a few extra pickets: some will be bowed or split, and you will want spares for repairs.
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Tools & materials for this project
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Frequently asked questions
How far apart should fence posts be?
Eight feet on center is standard for wood fences, and six feet suits heavy privacy fences or windy sites. Prefab panels dictate the spacing (usually 6 or 8 ft).
How many pickets do I need per foot?
Divide 12 by the picket width plus gap. A 1×6 (5.5 in) picket with no gap needs 2.2 pickets per foot of fence.
How many rails does a fence need?
Two rails for fences up to about 4 ft, and three rails for 5 to 6 ft privacy fences. Eight-foot fences may need four.
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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.