Fence Calculator
Plan the materials for a wood picket or privacy fence. Enter the total length, the post spacing and the picket size to get the number of posts, rails, pickets and bags of concrete for the post holes.
- Rails
- 26 rails
- Pickets
- 219 pickets
- Concrete (80 lb bags)
- 22 bags
- Sections
- 13
How this calculator works
The fence is divided into sections of the post spacing you choose. The number of sections is rounded up, and you need one more post than sections.
Rails are the number of sections multiplied by the rails per section. Pickets are the fence length in inches divided by the picket width plus the gap.
Concrete per hole is the volume of a cylinder (π × radius² × depth) minus the volume taken up by a 4×4 post (3.5 × 3.5 in actual size). Bags assume 80 lb premix, which yields about 0.6 cu ft.
Example: 100 ft of picket fence with posts every 8 ft
- Sections: 100 ÷ 8 = 12.5, rounded up to 13.
- Posts: 13 + 1 = 14.
- Rails: 13 sections × 2 rails = 26.
- Pickets: 1,200 in ÷ (3.5 in + 2 in gap) = 218.2, so 219 pickets.
- Concrete: 14 holes × 0.92 cu ft ÷ 0.6 = 21.5, so 22 bags of 80 lb.
Quick reference
| Fence length | Sections | Posts |
|---|---|---|
| 50 ft | 7 | 8 |
| 100 ft | 13 | 14 |
| 150 ft | 19 | 20 |
| 200 ft | 25 | 26 |
Tips before you buy
- Add one extra post for each gate and each corner beyond the first straight run, and plan gate posts with deeper holes.
- Call 811 before you dig so underground utilities are marked for free.
- Check your local rules and HOA guidelines for maximum fence height and setbacks from the property line.
Frequently asked questions
How far apart should fence posts be?
Wood fence posts are typically 6 to 8 feet apart. Use 6 feet in windy areas or for tall privacy fences, and never more than 8 feet.
How deep should fence post holes be?
A common rule is one third of the post height above ground, and at least 2 feet. In cold climates, dig below the frost line.
How many bags of concrete per fence post?
A 10 inch hole that is 2 feet deep with a 4×4 post needs about 0.9 cubic feet of concrete — roughly 1.5 bags of 80 lb premix per post.
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Last updated October 25, 2026