Fence Calculator
Posts, rails, pickets or panels, post-hole concrete and a materials budget — with gates and corners handled properly.
Fences are a fencepost problem
A 48-ft run needs one more post than it has sections — the classic off-by-one. Drag the maximum spacing to see how posts, holes and rails trade off.
Between 6 and 8 ft is the sweet spot: standard 8-ft rails and panels fit, and wind load per post stays reasonable. Spacing is always evened out along the run, so you never end with a stubby last section.
Fence material formulas
sections = ⌈run length ÷ spacing⌉ · posts = sections + 1 per run
pickets = fence length (in) ÷ (picket width + gap)
Every gate and corner starts a new straight run, and each run needs its own end post, so they add posts even when the length doesn’t change. Gate openings are subtracted from the length that gets pickets or panels; gate posts should be heavier (6×6 or steel) because they carry the swinging load.
Post length by fence height
| Fence height | Bury depth | Post length |
|---|---|---|
| 3 ft | 2 ft | 5 ft |
| 4 ft | 2 ft | 6 ft |
| 5 ft | 2 ft | 7 ft |
| 6 ft | 2 ft | 8 ft |
| 8 ft | 3 ft | 11 ft |
Questions people ask
How many fence posts do I need?
Divide the fence length by the post spacing, round up to get the number of sections, then add one post for the end — plus one extra for every gate and corner that interrupts the line. A 100-ft straight fence at 8-ft spacing has 13 sections and 14 posts.
How many pickets do I need for a fence?
Divide the fence length in inches by the picket width plus the gap. With 5½-inch pickets and a 2-inch gap, each picket takes 7½ inches, so 100 ft (1,200 in) needs 160 pickets. For a privacy fence with no gap, 1,200 ÷ 5.5 = 219 pickets. Add 5% for culls.
How far apart should fence posts be?
Six to eight feet on centre for wood fences, with 8 ft being the most common because rail lumber comes in 8-ft lengths. Vinyl and aluminium panel fences use the panel width, typically 6 or 8 ft. Chain link posts are usually 10 ft apart.
How deep should fence posts be set?
A common rule is one-third of the post’s above-ground height, and at least 24 inches — deeper than the local frost line in cold climates. A 6-ft privacy fence usually uses 8-ft posts set about 2–3 ft deep.
How much concrete per fence post?
For a 4×4 in a 10-inch-diameter, 30-inch-deep hole, about 1.1 cubic feet — two 50-lb bags of fast-setting mix. A 6×6 in a 12-inch hole 36 inches deep takes about 1.6 cubic feet, around three 60-lb bags.
How much does a fence cost per foot?
Installed prices in the US commonly range from about $15–$30 per linear foot for chain link, $20–$45 for wood privacy and $25–$50 for vinyl, with ornamental aluminium or steel higher. DIY materials are roughly a third to half of installed prices.