Fence Calculator

US & Canada

Enter your fence length and post spacing to get the posts, rails, pickets and bags of concrete to buy.

Your fence

1. Fence line

ft
ft
gates
ft

8 ft spacing is common for wood fences and matches 8 ft rails. Check your local bylaw for height and setback rules.

2. Rails and pickets

in
in

A 1x6 picket is 5 1/2 in wide. Use 0 gap for a privacy fence.

3. Post holes

in
ft

Go below your local frost depth, which your municipality can confirm. Many Canadian deck guides use 1.2 m (4 ft), Winnipeg 1.8 m.

Result

0

Shopping list

Posts include one extra per gate. Concrete has the post's volume taken out. Gate hardware is not included.

How the fence maths works

  • Sections = fence length ÷ post spacing, rounded up
  • Posts = sections + 1, plus 1 per gate
  • Rails = sections (less gate openings) × rails per section
  • Pickets = fenced length ÷ (picket width + gap), rounded up
  • Concrete per post = hole volume − post volume, then divided by bag yield

Materials for common fence lengths

8 ft spacing, three rails, 5 1/2 in pickets with no gap, 4 × 4 posts in 10 in holes 3 ft deep.

Posts, rails, pickets and concrete for common fence lengths
Length Posts Rails Pickets 80 lb bags
50 ft 8 21 110 19
100 ft 14 39 219 33
150 ft 20 57 328 47
200 ft 26 75 437 60
300 ft 39 114 655 90

Bag yields: 80 lb makes 0.6 cu ft, 50 lb makes 0.375 cu ft, 30 kg makes 0.449 cu ft, as printed on common bags.

Before you dig

  • Call before you dig. Have underground lines located (811 in the US, Ontario One Call or your province's service in Canada).
  • Check the bylaw. Height limits, setbacks and pool fence rules are set locally.
  • Find the property line. A survey avoids building on the neighbour's land.

Common questions

How many fence posts do I need for 100 feet?
At 8 ft spacing, 100 ft of fence is 13 sections, so 14 posts: one per section plus the end post. Add one more for every gate.
How many pickets do I need for 100 feet of fence?
With 5 1/2 in pickets butted tight for privacy, 219 pickets. Leave gaps and you need fewer: the calculator works it out for any picket width and gap.
How many posts for 150 feet of fence?
At 8 ft spacing, 20 posts and 57 rails for a three-rail fence, plus 328 pickets 5 1/2 in wide.
How many bags of concrete per fence post?
For a 10 in hole 3 ft deep around a 4 × 4 post, each hole takes about 3.7 bags of 50 lb concrete or 2.3 bags of 80 lb. For 100 ft of fence that is 33 bags of 80 lb in total.
How deep should fence posts be?
Below the local frost line, so frost cannot heave them. No building code sets fence post depth, so ask your municipality. Many Canadian deck guides use 1.2 m (4 ft) for footings, and Winnipeg 1.8 m. Deeper holes need more concrete, which the calculator handles.
How far apart should fence posts be?
8 ft is the usual spacing for wood fences because rails are sold in 8 ft lengths. Use 6 ft for heavy or tall fences, or where wind load is high.
How many rails does a fence need?
Two rails for a fence up to about 4 ft, three for a 6 ft privacy fence. For 200 ft at 8 ft spacing, a three-rail fence needs 75 rails.