How Much Do I Need?

Fence Calculator

How much fencing do I need?

Enter the length of the fence and how far apart the posts go. The calculator works out the sections and posts, then panels or pickets and rails, and the concrete to set each post.

Units
Fence

Centre to centre. Match your panel width, often 6 or 8 ft (1.8 or 2.4 m).

A fence with a corner is two runs. Each run needs its own end post.

Post holes

Often about three times the post width.

Often a third to a half of the post height above ground; deeper where the ground freezes.

A "4×4" post is actually 3.5 in (about 9 cm) across.

An 80 lb bag of concrete mix makes about 0.6 ft³ (17 L). Check the bag.

For damaged pickets and spilled concrete.

Cost (optional)

Add the price to see an estimated total.

Results update as you type.

Your estimate

Fence materials

14 posts, 13 panels

23 bags of concrete for the posts.

Estimated amount to buy

Posts
14
Panels
13
Concrete bags (0.6 ft³ each)
23

Calculated quantity (no extra)

Sections
13
Concrete per post
0.92 ft³
Concrete for all posts
12.89 ft³
How this was calculated
  1. Sections = 100 ft ÷ 8 ft = 12.5, rounded up to 13
  2. Posts = 13 sections + 1 end post = 14
  3. Concrete per hole = π × (10 in ÷ 2)² × 24 in − the post (3.5 in² × 24 in) = 0.92 ft³
  4. Bags = 14 posts × 0.92 ft³ × 1.05 ÷ 0.6 ft³ per bag = 22.56, rounded up to 23
  • Gates: subtract each gate opening from the fence length, and add the gate posts, which are often heavier.
  • Check where buried cables and pipes run before digging, and any local rules on fence height.

How the fence calculation works

  1. Sections = fence length ÷ post spacing, rounded up. Each extra straight run adds one more section, because a run rarely ends exactly on a full panel.
  2. Posts = sections + one end post per run.
  3. Panels = sections. For a picket fence, pickets = length ÷ (picket width + gap), plus the extra, and rails = sections × rails per section.
  4. Concrete per post = the volume of the hole (π × radius² × depth) minus the part of the post inside it.
  5. Bags = concrete for all posts, plus the extra, ÷ the yield of one bag, rounded up.

Setting posts

A common rule of thumb is a hole about three times the width of the post, and deep enough to bury a third to a half of the post's height above ground, often 2 ft (60 cm) or more for a 6 ft fence. Where the ground freezes, holes usually go below the frost line. Many people put a few inches of gravel in the bottom of each hole for drainage, which slightly reduces the concrete needed.

Rounding rules

  • Sections, pickets and bags are rounded up.
  • With several runs, the count allows a part section at the end of every run, so it may leave you a spare panel or rails.