Fence Calculator
A wood fence is three material lists: pickets, posts, and rails. Enter your run length and the calculator builds all three.
Fence Calculator
About this fence calculator
Fence estimating breaks into three independent counts. Pickets = total inches of fence divided by (picket width + gap). Posts = number of 8-foot sections plus one. Rails = two per section for a standard privacy fence (three for tall or high-wind fences). Get those three right and the materials list is done.
The gap setting is where designs diverge. A true privacy fence uses zero gap; shadowbox and spaced-picket styles use 1–3 inches. Note the gap also changes your picket count — a 2-inch gap on 5.5-inch pickets cuts picket needs by more than a quarter, which is real money on a long run.
Posts are the structural heart. Set them 2–3 feet deep (below frost line in cold climates), in concrete, and use pressure-treated or cedar posts rated for ground contact. A fence fails at the posts years before the pickets give out — this is not the place to economize.
Worked example: materials for a 100-ft privacy fence
Take a 100-ft fence run with 5.5-inch-wide pickets, no gap, and posts every 8 feet. Pickets: 100 ft = 1,200 inches ÷ 5.5 = 218.18, rounded up to 219 pickets. Posts: 100 ÷ 8 = 12.5 sections, rounded up to 13 sections, plus 1 = 14 posts. Rails: 13 sections × 2 rails = 26 rails.
That is the lumber order in one pass: 219 pickets, 14 posts, 26 rails. Add concrete (about one 50-lb bag per post — 14 to 16 bags) and fasteners, and you have the full shopping list. The posts are the part people underbuy: a fence is only as strong as its posts, so do not shave this number.
Buying tips
Pressure-treated posts rated for ground contact are non-negotiable — standard treated lumber rots at the soil line in a few years. For gate posts, step up to 6×6 posts set in extra concrete; gates are heavy and they rack ordinary 4×4 posts within a season or two.
Before you buy anything, confirm the property line (a survey is cheaper than moving a fence), check HOA rules on height and style, and call 811 to mark utilities before you dig — hitting a gas or fiber line turns a weekend project into a very expensive day. Local codes often cap front-yard fences at 3–4 ft and side/back at 6–8 ft.
How to use
- Measure the total fence length in feet, following the actual line including gates (subtract gate openings).
- Enter picket width (5.5 in for nominal 1×6) and your gap (0 for privacy).
- Set post spacing — 8 ft is standard for wood privacy fences.
- Press Calculate for pickets, posts, rails, and a concrete rule-of-thumb.
Good to know
- Straight runs only — measure each straight section separately and add the results.
- Gates need their own hardware (hinges, latch, gate frame kit) and are excluded from picket counts.
- Concrete figure is a rule of thumb (~1 bag per hole); verify hole volume with the concrete calculator.
- Check property lines, HOA rules, and local height/setback codes before you dig — and call 811 for utilities.
- Set posts at least 2 ft deep (one-third of post height for taller fences) and bell out the bottom of the hole — it resists frost heave far better than a straight-sided hole.
- Budget about one 50-lb bag of concrete per post for a typical 6-ft privacy fence. Dry-packing (tamping dry mix and letting ground moisture set it) works in many soils and skips the mixing.
Frequently asked questions
How many fence pickets do I need for 100 feet?
With 5.5-inch pickets and no gap: 100 × 12 ÷ 5.5 = 219 pickets (rounded up). Add 5–10% for culls and bad boards.
How far apart should fence posts be?
8 feet on center is standard for wood privacy fences. Wider spacing sags; closer spacing wastes posts and concrete.
How many bags of concrete per fence post?
Roughly one 50–60 lb bag per post hole for a typical 10-inch-diameter, 2.5-foot-deep hole. For exact numbers, measure your hole and use the concrete calculator.
How do you calculate a fence?
Pickets = fence inches ÷ (picket width + gap); posts = sections + 1; rails = 2 per section.
Should there be a gap between fence pickets?
Zero gap for privacy. Spaced pickets (1–3 in gaps) suit decorative or airflow designs and use fewer pickets.
How deep should fence posts be?
At least 2 feet, or one-third of the total post height — a 6-ft fence needs 8-ft posts with 2 ft in the ground. In frost country, set posts below the local frost line or heaving will loosen them within a couple of winters.
How much concrete do I need per fence post?
Roughly one 50-lb bag per post for a standard 10-inch-wide, 2-ft-deep hole. For a 14-post fence, buy 14–16 bags — the extras cover the inevitable hole that ends up wider than planned.
Is 6 ft or 8 ft post spacing better?
8 ft is the standard for wood privacy fences and uses fewer posts and less concrete. 6 ft spacing is stronger — better for tall fences, high-wind areas, or heavy gates — it just costs more. Enter your spacing above and the calculator handles either.
How do I account for a gate in the fence run?
Measure each gate opening separately and subtract it from the total fence length before calculating. A gate needs its own heavier posts (6×6 recommended) set in extra concrete, plus hinges and a latch — budget those separately since this calculator covers the straight run.