Fence Calculator
Enter your fence length and style to calculate the exact number of posts, rails, pickets, and bags of concrete you'll need. Add gates and adjust post spacing to match your design.
Fence Details
Use 0 for a solid privacy fence
Materials Needed
Line Posts
Rails / Stringers
Pickets / Boards
Concrete Bags (50 lb)
Bays (Panels)
Fence Line (ft)
Pickets include a 10% waste allowance. Concrete is estimated at 2 bags per post hole (for a 6-ft post in a 10-in diameter, 24-in deep hole).
How to Estimate Fence Materials
Building a fence involves four main components: posts, rails (horizontal stringers), pickets (vertical boards), and concrete for the post footings. Here's how each is calculated:
Posts
The number of line posts = fence length ÷ post spacing + 1 (for the end post), minus any gate spans. Corner posts and end posts are counted but not separately itemized here — budget 1–2 extra posts for each corner and gate post pair you add beyond a straight run.
Post length should be 1/3 taller than the fence height to allow for setting in the ground. A 6-ft fence needs 9-ft posts (6 ft above grade, 3 ft below).
Rails
Number of rails = bays × rails per bay. Rail length should match the post spacing (typically 8-ft lumber for 8-ft spans, or two 6-ft pieces for 6-ft bays).
Pickets
Number of pickets per bay = bay width (in inches) ÷ (picket width + gap). Multiply by total bays for the full picket count. The calculator adds a 10% waste factor for cuts and damaged boards.
Concrete
Each post should be set in concrete for stability. A rule of thumb is 2 bags of 50-lb concrete per post for a hole 10 inches in diameter and 2 feet deep (for a 6-ft fence). Taller fences or soft soil may require deeper, wider holes. Check with your local building department for code requirements.
Post concrete footings need to cure before the fence is built. To estimate how many bags of concrete you'll use overall — including for other structures — see the concrete calculator.
Frequently Asked Questions
How deep should fence posts be set?
A common rule is to bury at least 1/3 of the total post length, or a minimum of 2 feet deep — whichever is greater. In frost-prone regions, posts must go below the frost line (typically 3–4 feet in the northern U.S.) to prevent heaving. Check your local frost depth before digging.
What wood is best for fence pickets?
Pressure-treated pine, cedar, and redwood are the most popular choices. Cedar and redwood are naturally rot-resistant and won't warp as badly. Pressure-treated pine is cheaper upfront but may require more maintenance. All should be sealed or stained within the first year.
Do I need a permit to build a fence?
Many municipalities require a permit for fences above a certain height (often 4–6 feet) or near a property line. Always check local zoning rules and HOA guidelines before starting. Contact your local building department — permit requirements vary widely.
Should I use concrete for all posts?
Yes for most situations, especially for gate posts and corner posts which endure the most stress. Some installers use compacted gravel for line posts in sandy or well-draining soil, but concrete is the most reliable for long-term stability. Avoid fast-setting concrete mixes that can crack in freeze-thaw cycles.
