Fence calculator
Enter the total run of fence and how you plan to build it. The calculator counts posts, rails, pickets, and the bags of concrete to set the posts, so you can price the whole job before buying a single board.
How the fence calculator works
The calculator subtracts the gate openings from the total length, then divides what is left by the post spacing to get the number of fence sections. Posts equal sections plus one, with extra posts added for each additional corner and for each gate. Rails are sections multiplied by rails per section, and pickets are the total run in inches divided by the picket width plus gap.
Concrete is figured per post. Two 50 lb bags fill a typical 10 inch diameter hole 24 inches deep around a 4x4 post. Use the concrete calculator if your holes are a different size.
Formula
sections = (length − gate openings) ÷ post spacing, rounded up
posts = sections + 1 + extra corners + gates
pickets = run in inches ÷ (picket width + gap)
Example: a 100 ft privacy fence with one 4 ft gate and 8 ft post spacing has 96 ft of panels, 12 sections, and 16 posts (13 along the run, plus 2 extra corners and 1 for the gate). Three rails per section is 36 rails. With 5.5 in pickets and no gap, 96 × 12 ÷ 5.5 = 210 pickets, or 231 with 10 percent waste.
Planning tips
- Call 811 before digging. Utility locating is free and required in most states.
- Check your property line and local height limits. Many cities cap front-yard fences at 4 ft and backyard fences at 6 ft.
- Pressure-treated pine pickets cost the least; cedar costs more but resists rot and weighs less. Posts should always be pressure-treated and rated for ground contact.
- Set posts below the frost line in cold climates, typically 30 to 42 inches, so frost heave does not push them up.
- Let pressure-treated wood dry for a few weeks before staining.
Common questions
How many fence posts do I need for 100 feet?
14 posts with 8 ft spacing, or 18 posts with 6 ft spacing, counting the two end posts on a straight run. Add one post for every gate and every corner beyond the first two ends.
How many pickets do I need for a 6 ft privacy fence?
About 22 pickets per 10 feet of fence using 1x6 dog-ear pickets butted together with no gap. A 100 ft fence needs around 210 pickets plus 10 percent for waste and splits.
How deep should fence posts be?
One third of the above-ground height is the rule of thumb, so a 6 ft fence uses 8 ft posts set 2 ft deep. In freezing climates, go below the frost line, which may mean 3 ft or more.
How many bags of concrete per fence post?
Two 50 lb bags, or one 80 lb bag, per 4x4 post in a 10 inch hole 2 ft deep. Larger 6x6 posts or windy sites call for three bags. Fast-setting mix can be poured dry and watered in place.