Fence Calculator: Posts, Rails, Pickets & Panels
Estimate the posts, rails, pickets (or prefab panels) and post concrete for a wood fence, including gates.
A 100-ft fence with posts every 8 feet needs 14 posts (13 sections plus one), 26 rails if each section has two, and about 219 pickets of 5.5 inches with no gaps. Add one post per gate and about 5% extra pickets.
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How to estimate a wood fence
A basic fence is a repeating section: two posts, a few horizontal rails between them, and vertical pickets across the rails. Work out how many sections the fence has, then the parts for each. Prefab panels replace the rails and pickets with one ready-made panel per section.
posts = sections + 1 (+ 1 per gate)
pickets = fence length × 12 ÷ (picket width + gap) × (1 + waste %)
rails = sections × rails per section
Posts needed by fence length
| Fence length | Posts at 6 ft | Posts at 8 ft | Pickets (5.5 in, no gap) |
|---|---|---|---|
| 50 ft | 10 | 8 | 110 |
| 100 ft | 18 | 14 | 219 |
| 150 ft | 26 | 20 | 328 |
| 200 ft | 35 | 26 | 437 |
| 300 ft | 51 | 39 | 655 |
Post depth and concrete
Posts should be set at least one-third of their length in the ground, and below the frost line where it is required. Use the post hole concrete calculator for exact bag counts; the estimate above assumes two 80-lb bags per post.
Choosing post and rail sizes
| Fence height | Post length | Rails |
|---|---|---|
| 4 ft | 6–7 ft (4×4) | 2 |
| 6 ft | 8–9 ft (4×4 or 4×6) | 3 |
| 8 ft | 10–11 ft (6×6) | 4 |
Fence styles and what they need
| Style | Typical height | Pickets / panels |
|---|---|---|
| Privacy (board-on-board) | 6 ft | Pickets side by side or overlapped |
| Picket | 3–4 ft | Pickets with 1.5–3 in gaps |
| Split rail | 3.5–4 ft | No pickets, 2–3 rails |
| Prefab panel | 6 ft × 6 or 8 ft | One panel per section |
Check before you build
- Many towns limit fence height (often 4 ft in front yards and 6 ft in back yards) and require permits.
- Confirm your property line with a survey before digging.
- Call 811 before digging to mark underground utilities.
Frequently asked questions
How many fence posts do I need for 100 feet?
With posts every 8 feet you need 14 posts for 100 feet (13 sections plus one), plus an extra post for each gate. At 6 feet spacing you need 18.
How many pickets per foot of fence?
A privacy fence of 5.5-inch boards with no gap needs about 2.2 pickets per foot of fence.
How far apart should fence posts be?
Six to eight feet on center is standard. Use six feet for heavy privacy panels or windy sites.
How many rails does a 6-foot fence need?
Three horizontal rails (top, middle and bottom) are standard for fences 5–6 feet high.
How many pickets do I need for a 6-ft privacy fence of 100 feet?
About 219 pickets of 5.5 inches with no gaps, or about 230 with 5% waste.
How deep should fence posts be?
At least one-third of the post length, usually 24–36 inches for a 6-foot fence, and below the frost line where required.
How many bags of concrete per fence post?
About two 80-lb bags per post in a 10-inch hole 30 inches deep.
Do I need a permit for a fence?
Often yes, especially above 6 ft or near a property line. Check with your local building department.
Sources and further reading
- Call 811 before you dig — Common Ground Alliance
These references support the general guidance on this page. The calculator applies the standard formulas shown above to the numbers you enter.
Related calculators
. Estimates only. Always confirm quantities with your supplier or a qualified contractor before ordering, and add extra for waste and site conditions.