Enter your fence line’s length and post spacing to get the materials — posts and pickets counted for you.
What Is a Fence Calculator?
A fence calculator counts the two big material items: posts (one every N feet, plus one for the end) and pickets (fence length divided by picket-plus-gap width). For a 100 ft run at 8 ft spacing: ceil(100/8) + 1 = 14 posts. With 5.5-inch pickets and 0.5-inch gaps, each picket occupies 6 inches: 100 × 12 ÷ 6 = 200 pickets. Rails, concrete and hardware come after — but posts and pickets are the order that matters.
How to Use the Fence Calculator
- Enter the total fence length in feet.
- Enter the post spacing (8 ft is standard).
- Enter picket width and gap.
- Click “Calculate Fence” for posts and pickets.
Fence Calculator Formula
Posts = ceil(length ÷ spacing) + 1. Pickets = ceil(length in inches ÷ (picket width + gap)).
Worked Example
100 ft at 8 ft spacing → 14 posts. 5.5-inch pickets with 0.5-inch gaps → 200 pickets.
How It Works, In Plain Words
The tool counts the two materials separately, because they are counted in different ways. Posts first: your fence length is divided by the post spacing to get the number of sections, rounding up, because a part-section still needs a full bay. A 100 ft fence at 8 ft spacing gives 12.5, which rounds up to 13 sections. Then comes the step everyone forgets: a run of sections needs a post at both ends of every section, so the tool adds one — 13 sections, 14 posts. Pickets second: the length is converted to inches (100 ft is 100 × 12), and each picket is treated as occupying its own width plus one gap — 5.5 + 0.5 = 6 inches in the example. Dividing 1,200 inches by 6 inches gives exactly 200 pickets, again rounding up so a part-picket at the end is still ordered. The result line repeats your inputs back, so you can check at a glance that the count matches the fence you meant to describe before you order anything.
Real-World Uses
The standard job is a back garden privacy fence on a straight boundary — the worked example itself: 100 ft at 8 ft spacing needs 14 posts and 200 pickets, a list you can hand to a timber merchant as it stands. The second case is a run broken by a gate: measure the run, subtract the gate opening before you enter the length, and count the gate posts and hardware separately, exactly as the gate FAQ below advises — otherwise you will order pickets for a stretch of fence that will never exist. The third case is a plot with corners or a slope: run the tool once for each straight side rather than bending one measurement around the corner, and expect extra posts where the direction changes or the ground falls, because corners and slopes need posts of their own that a single straight-run count cannot see.
Benefits of a Fence Calculator
- Posts and pickets counted with real trade conventions
- The +1 end post is included (the classic miss)
- Picket gap adjustable for privacy vs spaced styles
- Straightforward for straight runs
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device.
Common Mistakes to Avoid
- Forgetting the end post — fence sections need a post at both ends
- Measuring around gates as one run: subtract gate openings from the length
- Not accounting for corners and slopes, which need extra posts
More Common Mistakes to Avoid
The costliest mistake is counting sections and calling it posts: 100 ft at 8 ft spacing is 13 sections but 14 posts, because every run ends with a post — order 13 and the last bay has nothing to fix to. Second, measure the fence you will actually build: subtract gate openings from the length before entering it, and add gate posts separately. Third, do not divide the length by the picket width alone: each picket occupies its width plus one gap — 6 inches in the example, not 5.5 — and forgetting the gap overstates how far each picket reaches, leaving you short near the end. Finally, treat corners and slopes as their own runs with their own end posts, rather than stretching one straight measurement around them.
Frequently Asked Questions
How many posts for a 100 ft fence at 8 ft spacing?
14 posts.
How many pickets for 100 ft with 5.5-inch pickets?
200 pickets with a 0.5-inch gap (each picket occupies 6 inches).
What is standard post spacing?
8 feet is standard for wood privacy fences; 6–10 ft is the common range.
How deep should fence posts be?
Typically one-third of the post length, minimum about 2 ft, set in concrete — below the frost line in cold climates.
Do I need a gate?
Count gates separately: subtract the gate opening from the run and add gate posts plus hardware.
Why does the post count add one at the end?
Because posts stand at the ends of sections, not inside them. 100 ft at 8 ft spacing makes 13 sections, and 13 sections need a post at both ends of the run — 14 posts. Forgetting that final post is the classic miss, so the tool builds it in.
Does the tool count rails, concrete and hardware?
No — it counts posts and pickets, the order that matters. Rails, concrete and hardware come after, as the introduction says; the post count still tells you how many holes you will dig, and each post is typically set in concrete about one-third of its length deep, minimum about 2 ft.