Fence calculator
Add each straight run of fence. You get the posts, pickets and rails, the post length to buy, and the concrete to set the posts.
Inputs
Result
| Item | Order |
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How it is worked out
A 100 ft run at 8 ft spacing is 13 sections and 14 posts. Six-foot fence takes three rails a section, so 39 rails, and 1x6 pickets side by side take 219. The posts go 36 in deep, so each is 9 ft long and you buy 10 footers.
Post depth
The usual rule is to bury a third of the post, which works out to half the height above ground: 36 in for a 6 ft fence. Go deeper where the ground freezes, so the bottom of the hole is below the frost line, and on windy, exposed sites. Holes are about three times the post's width across, 10 to 12 in for a 4x4.
Gates
Each gate needs a post on both sides. The calculator adds one post per gate, since one side usually lands on a post that was already there. Hang gates on 6x6 posts or set the gate posts deeper if the gate is wide or heavy.
Questions
How many fence posts do I need?
Divide each straight run by the post spacing, round up, and add one. Runs that meet share a corner post, and each gate adds one more. 100 ft at 8 ft spacing is 14 posts.
How many pickets for 100 feet of fence?
219 standard 5-1/2 in pickets laid side by side. With a 2-1/2 in gap, 150. Board on board with a 1 in overlap takes about 267.
How deep should fence posts be?
A third of the post's length, so half the fence's height: 36 in for a 6 ft fence, 24 in for a 4 ft one. Deeper in frost country, below the frost line.
How many bags of concrete per fence post?
For a 4x4 in an 11 in hole 36 in deep, about 1.7 cu ft, which is three 80 lb bags. A 10 in hole 30 in deep takes two.
How far apart should fence posts be?
8 ft on centre is standard for wood privacy fence, and it lets you use 8 ft rails. 6 ft spacing makes a stiffer fence in high wind.
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