Smart Unit ConvertersSmart Unit Converters

Fence Calculator

Estimate posts, panels, rails, and concrete bags for a fence. Plan-view diagram + 60lb / 80lb concrete bag counts.

Construction

Fence Calculator

Generated on April 25, 2026

6-8 ft typical for residential

2-3 horizontal rails typical

1/3 of post above-ground height

Plan view (15 posts)

100 ft total · 1 gate
Materials
Posts
15
Panels / sections
12
Rails
39
Sections
13
Concrete
10.5 ft³
60 lb bags
24
80 lb bags
18
Gates
1

Step-by-step calculation

Formula

# posts = ceil(length / spacing) + 1 + gates. # sections = ceil(length / spacing). # rails = sections × rails-per-section. Concrete per post = π·(4/12)²·depth (8-inch hole).

  1. 1Length: 100 ft, post spacing: 8 ft.
  2. 2# sections = ceil(100 / 8) = 13.
  3. 3# posts = 13 + 1 (end) + 1 (gate posts) = 15.
  4. 4# rails = 13 × 3 = 39.
  5. 5Concrete per post (8-inch diameter hole, 2 ft deep) = π × (4/12)² × 2 ≈ 0.70 ft³.
  6. 6Total concrete: 10.47 ft³ → 24 × 60 lb bags or 18 × 80 lb bags.

?What is the Fence Calculator?

The Fence Calculator estimates how many posts, fence panels (or sections between posts), horizontal rails, and bags of concrete you'll need for a fence project. Inputs: total length, post spacing (typically 6-8 ft for residential), number of gates (which add an extra post), rails per section, and post-hole depth. Outputs include both 60 lb and 80 lb concrete bag counts based on a standard 8-inch-diameter post hole. Useful for residential boundary fences, deck/patio enclosures, and agricultural perimeters.

The Formula

# posts = ceil(length ÷ spacing) + 1 + gates. # sections = ceil(length ÷ spacing). # rails = sections × rails-per-section. Concrete per post (8″ hole) = π × (4/12)² × depth_ft ≈ 0.349 × depth ft³.

Each gate requires its own post (the 'hinge post'), so add one extra post per gate to the formula. The +1 in the post count accounts for the closing end of the fence run. For concrete: an 8-inch-diameter post hole 2 ft deep takes about 0.7 cubic feet of concrete; a 60 lb bag yields ~0.45 ft³ and an 80 lb bag yields ~0.6 ft³. Rule of thumb: post hole depth = 1/3 of the post's above-ground height, so a 6 ft fence needs 2 ft holes.

Practical Examples

1

100 ft fence, 8 ft spacing, 1 gate: ceil(100/8) = 13 sections + 1 end + 1 gate = 15 posts.

2

Concrete: 15 posts × 0.7 ft³ ≈ 10.5 ft³ → 24 × 60 lb bags or 18 × 80 lb bags.

3

200 ft of agricultural fence (livestock) typically uses 10-12 ft post spacing, 4 strands of barbed wire (4 'rails' equivalent).

4

Privacy fences (6-8 ft tall) use 8 ft spacing and 3 horizontal rails (top, middle, bottom).

5

Picket fences (3-4 ft) use 8 ft spacing and 2 rails. Don't forget end-of-row gate posts.

Frequently Asked Questions

Standard fence panels (and rolls of chain link) are 6-8 ft wide. Match the spacing to your panel width so you don't have to cut. For wood-rail fences, 8 ft is the most common because lumber is sold in 8 ft lengths.

Popular Conversions

Jump to a ready-made conversion — useful for quick reference and sharing:

Explore More Tools

Tile Calculator

Calculate the number of tiles needed for any floor or wall, plus waste.

Paint Calculator

Calculate liters of paint needed for walls, accounting for doors and windows.

Concrete Calculator

Calculate cement, sand, and aggregate quantities for your concrete mix.