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This fence calculator estimates the materials for a wood picket, board or panel fence. Enter the length of the fence, the post spacing and the height, and it tells you how many posts, rails, pickets or panels you need, plus how much concrete to set the posts.
How to Use the Fence Calculator
- Choose a picket or board fence built on site, or a fence made from pre-made panels.
- Enter the total length of the fence line.
- Enter the post spacing. Wood fences commonly use 6–8 ft (1.8–2.4 m); panel fences match the panel width.
- For picket fences, enter the number of rails per section, the picket width and the gap between pickets.
- Choose the post size and the diameter and depth of the post holes.
Fence Formulas
Sections = Fence length ÷ Post spacing (rounded up)
Posts = Sections + 1
Pickets = Fence length ÷ (Picket width + Gap)
Concrete per post = π × (Hole diameter ÷ 2)² × Depth − Post volume
The calculator assumes one straight run of fence. Each corner, gate or change of direction usually needs one extra post.
Worked Example: 100 ft Picket Fence
- Post spacing 8 ft: 100 ÷ 8 = 12.5, so 13 sections and 14 posts
- Two rails per section: 26 rails of 8 ft
- 3.5 in pickets with 0.5 in gaps: 1,200 in ÷ 4 in = 300 pickets
- Holes 10 in wide and 2 ft deep with 4×4 posts: about 12.9 cu ft of concrete, or 35 bags of 50 lb fast-setting concrete
Metric example: a 30 m panel fence using 1.83 m panels needs 17 panels and 18 posts. With 25 cm holes 60 cm deep and 100 mm posts, you need about 45 bags of 20 kg post mix.
Typical Fence Dimensions
| Item | Common sizes |
|---|---|
| Post spacing | 6–8 ft (1.8–2.4 m) |
| Post size | 4×4 in or 6×6 in; 75 mm or 100 mm square |
| Post hole diameter | About 3 times the post width |
| Post hole depth | About 1/3 of the post length, below the frost line where required |
| Pickets | 3.5 or 5.5 in wide (about 9 or 14 cm) |
| Panels | 6 or 8 ft wide; 1.83 m (6 ft) in the UK |
Rails per Section
- Fences up to about 4 ft (1.2 m): 2 rails.
- Fences 5–6 ft (1.5–1.8 m): 3 rails are common for strength.
- Taller or exposed fences: 3 or more rails and closer post spacing.
Before You Build a Fence
- Confirm your property line and check local and HOA rules for height and setbacks.
- Call your local utility locating service before digging. In the US, dial 811.
- Gates need sturdier posts and hardware; plan them before setting the line posts.
- Setting posts in concrete? Our concrete calculator can size larger footings.
Frequently Asked Questions
How many fence posts do I need for 100 feet?
With 8 ft spacing, a straight 100 ft fence needs 13 sections and 14 posts. With 6 ft spacing it needs 17 sections and 18 posts. Add a post for each corner or gate.
How far apart should fence posts be?
Most wood fences use posts 6 to 8 feet (1.8 to 2.4 m) apart. Panel fences use spacing that matches the panel width.
How many pickets do I need per foot of fence?
Divide 12 inches by the picket width plus the gap. With 3.5 in pickets and a 0.5 in gap, you need 3 pickets per foot.
How much concrete do I need per fence post?
A 10 in wide, 2 ft deep hole around a 4×4 post needs about 0.9 cu ft of concrete, which is roughly two and a half 50 lb bags of fast-setting concrete.
How deep should fence posts be?
A common rule is to bury one third of the post length, and at least 2 ft (60 cm). In cold climates, go below the frost line.
Related guide: How Many Fence Posts Do I Need? (With Corners and Gates)
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