Fence Calculator – Posts, Rails & Pickets

Fence math is a layout problem. Posts: fence length ÷ post spacing + 1, with 2.4 m the working maximum - closer (2 m) in high wind or for heavy infill. Concrete: each hole of 25 cm diameter × 60 cm depth takes about 0.03 m³, i.e. one 40 kg bag per post. Rails: 2 per bay to 1.8 m height, 3 above. Pickets: length ÷ (picket width + gap). Worked example: a 30 m fence at 2.4 m spacing needs 13 posts of 3.6 m (0.8-1.2 m buried), 13 bags of concrete, 26 rails and about 150 pickets of 14 cm at 5 cm gaps. Cedar lasts 15-20 years untreated; pine needs pressure treatment for that lifespan.

1. 1

   Measure the space

   Record the fence length, height and style at the widest and longest points.

2. 2

   Enter the values

   Type the measurements into the calculator and select your units.

3. 3

   Apply the formula

   The tool computes Posts = Length ÷ Spacing + 1; Pickets = Length ÷ (Width + Gap); Concrete = Posts × 0.03 m³ for your inputs instantly.

4. 4

   Add waste and order

   Review the total with a 5-10% margin and round up to whole units.

• Using nominal as actual sizes

• Spacing joists too wide

• No ground-contact treatment