20 m run, 14 cm boards, 2 cm gaps
Input Run 20 m, height 1.8 m, boards 14 cm with 2 cm gaps, posts every 2.4 m, 2 rails.
Result 125 boards, 10 posts, 40 m of rail and 225 m of board in total.
Fence Calculator
Home & RenovationWork out pickets, posts, rails and total board length for a run of fence from spacing and board size.
Your inputs
Result
Boards needed
—
- Posts —
- Rail length — m
- Total board length — m
Change any input and the result updates instantly.
Formula and rules
- Boards = run ÷ (board width + gap), rounded up
- Posts = run ÷ post spacing, rounded up, plus one for the end
- Rail length = rails per bay × run
- Total board length = boards × fence height
- Add one extra board and post for gates, corners and waste
Worked examples
100 ft run, 5.5 in boards, 0.5 in gaps
Input Run 100 ft, height 6 ft, boards 5.5 in with 0.5 in gaps, posts every 8 ft, 2 rails.
Result 200 boards, 14 posts, 200 ft of rail and 1,200 ft of board in total.
FAQ
How far apart should fence posts be?
2.4 m (8 ft) is the usual maximum for timber posts. Use 1.8 m (6 ft) on exposed or windy sites, and set every post at least one-third of its length in concrete.
Should I count the gate as fence?
Deduct the gate opening from the run, then add the gate frame, hinges and two extra posts separately. Gates put far more load on a post than boards do.
How many rails does a fence need?
Two rails for fences up to 1.8 m (6 ft), three for taller fences or places that catch the wind. Rails are usually 2 × 4 timber laid flat.
Disclaimer: Results follow the formula shown on this page and are for reference only. Real-world quantities vary with materials, technique and conditions, so allow a margin before ordering.