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Generator Hut

Fence Calculator

Posts, rails, pickets and post concrete for a fence run.

Your measurements

8 ft is standard. 6 ft gives a stiffer fence in exposed positions.

Zero for a privacy fence, 2–4 in for a picket fence.

About 1 cu ft for a 4x4 in a 10 in hole, 2 ft deep.

Fence materials

14posts

14 posts, 39 rails, 219 pickets

Sectionsat 8 ft spacing
13
Postsone more than the number of sections
14
Rails3 per section
39
Picketsat 5.5 in wide plus a 0 in gap
219
Concrete for posts1 cu ft per post
14 cu ft
Bags of premixat 0.6 cu ft per bag
24 × 80 lb

Post count assumes a single straight run. Every corner, gate and change of direction needs its own post, so add one per corner and two per gate on top of this figure.

Post depth should be roughly a third of the above-ground height, and below the frost line wherever the ground freezes. A shallow post in frost-heaving soil will lift regardless of how much concrete surrounds it.

Gate hardware, post caps and fasteners are not included. Gates in particular need heavier posts than the run — a 4x4 that carries a gate all day will eventually lean.

Enter the fence length and post spacing and it returns posts, rails and pickets along with the concrete needed to set the posts. The picket gap field switches it between a solid privacy fence and a spaced picket fence.

Why use this tool?

Posts, rails and pickets

The three counts that determine the order, derived from one length measurement and your chosen spacing.

Post concrete included

Concrete volume for setting the posts, converted to 80 lb bags — the item most often forgotten until the posts are already in the holes.

Privacy or picket

Set the gap to zero for a solid fence, or 2 to 4 inches for a traditional picket layout.

Adjustable spacing

Eight feet is standard, six gives a stiffer fence in exposed positions. Both change the post and rail counts.

How this fence calculator works

Sections are the fence length divided by the post spacing, rounded up. Posts are always one more than the sections, because a run of fence is closed at both ends — the classic off-by-one that leaves people a post short.

Rails multiply by the sections, and pickets come from dividing the total run in inches by the width of one picket plus its gap. That per-picket unit is what makes the gap setting matter: a 2 inch gap on a 100 foot fence removes roughly 60 pickets from the order.

Concrete is calculated per post from the volume you enter, then converted to 80 lb bags at 0.6 cubic feet each. About one cubic foot suits a 4x4 in a 10 inch hole two feet deep.

How to use it

  1. Step 1: Measure the run

    The total length of fence. For a fence with corners, measure each straight run and add them, then add a post per corner to the result.

  2. Step 2: Choose post spacing

    Eight feet is standard and matches common rail lengths. Six feet is stiffer and worth it in windy or exposed positions.

  3. Step 3: Set the picket gap

    Zero for a solid privacy fence. Two to four inches for a picket fence, where the gap is part of the look.

  4. Step 4: Add gates and corners

    This assumes a straight run. Add one post per corner and two heavier posts per gate on top of the figure given.

Example usage

A 100 foot privacy fence
At 8 foot spacing that is 13 sections and 14 posts, 39 rails at three per section, and 219 pickets at 5.5 inches with no gap. The posts need about 14 cubic feet of concrete, or 24 bags.
The same run as a picket fence
Adding a 3 inch gap between pickets drops the picket count from 219 to 141 — a substantial saving, and the reason spaced pickets have always been the cheaper fence.
A fence with two corners
Three straight runs of 40, 30 and 30 feet total 100 feet, but each run closes with its own post. Calculate the total, then add two posts for the corners.

Frequently asked questions

How many fence posts do I need?

One more than the number of sections, because the run is closed at both ends. A 100 foot fence at 8 foot spacing has 13 sections and 14 posts — plus one extra per corner and two per gate.

How deep should fence posts be set?

Roughly a third of the above-ground height, and below the frost line wherever the ground freezes. A shallow post in frost-heaving soil will lift out over a winter regardless of how much concrete surrounds it.

How much concrete per fence post?

About a cubic foot for a 4x4 in a 10 inch diameter hole two feet deep — roughly two 80 lb bags. Deeper holes and larger posts need proportionally more, which the field above lets you set.

How far apart should fence posts be?

Eight feet is the standard, matching common rail lengths. Six feet gives a noticeably stiffer fence and is worth the extra posts in exposed positions or for tall privacy fencing that catches wind.

Does this include gate hardware?

No. Gates need heavier posts than the run, plus hinges, latches and often a diagonal brace. A standard 4x4 carrying a gate all day will eventually lean.

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