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Fence Post Spacing Calculator

Fence posts from the length and a maximum spacing: posts = ceil(length ÷ spacing) + 1, spread evenly, with gates, corners, rails, pickets and concrete. How it works

Use the Fence Post Spacing Calculator

Centre of the first post to centre of the last post, gates included.

Centre to centre. Posts are spread evenly, so the real spacing is this or less.

Used for the clear gap between posts.

Whole number, 0 to 10. Gate posts are counted in the total.

Whole number, 0 to 20. Corner posts are shared by two sides and counted in the total. Sides are assumed equal.

Bracing or terminal posts to add on top. Counted in the total and the concrete.

0 leaves rails out. Each rail runs post to post.

Leave blank to skip pickets.

The most space between pickets; it shrinks a little to fit a whole picket.

Post holes (for the concrete estimate)

Common sizes below. The hole must be at least as wide as the post.

Frost depth and local code can require more.

Posts needed
14
Sections 13

Breakdown

Actual spacing, centre to centre
7.69 ft
Clear gap between posts
7.36 ft
End posts
2
Gate posts
0
Line posts
12

Each run is cut into 13 sections of 7.69 ft (at most 8 ft), which takes 14 posts per run, 14 in all.

Concrete for the post holes

Per hole
1.36 cu ft
All 14 holes
19.09 cu ft
50 lb bags
51
60 lb bags
43
80 lb bags
32

Each hole is filled to the top and the post's own volume is not subtracted. Bag yields are approximate figures from the QUIKRETE No. 1101 data sheet (50 lb 0.375, 60 lb 0.45, 80 lb 0.60 cu ft).

Layout of one run
O─7.69 ft─O─7.69 ft─O─7.69 ft─O─7.69 ft─O─7.69 ft─O─7.69 ft─O─7.69 ft─O─…─O (14 posts in this run)

Gates are assumed to split the line into equal runs. Gates that are not evenly placed can need up to one more post per gate. The fence length is the total of all sides. Corners split the line into equal sides that share the corner post; sides of unequal length can need more posts, so for an irregular fence calculate each side on its own and subtract one post per corner. Check local building codes and the manufacturer's limits for the spacing you can use.

About the Fence Post Spacing Calculator

A 100 ft fence with posts at most 8 ft apart needs 14 posts: 100 ÷ 8 = 12.5, rounded up to 13 sections, plus one post. The fence post calculator spreads the posts evenly, so they stand 7.69 ft apart center to center, never more than the maximum. Gate posts are counted inside the total rather than added on top: the same 100 ft with two 6 ft gates is 15 posts, 4 of them gate posts.

Fence posts by length and maximum spacing

Fence length6 ft maximum8 ft maximum10 ft maximum
50 ft10 (5.56 ft)8 (7.14 ft)6 (10 ft)
100 ft18 (5.88 ft)14 (7.69 ft)11 (10 ft)
150 ft26 (6 ft)20 (7.89 ft)16 (10 ft)
200 ft35 (5.88 ft)26 (8 ft)21 (10 ft)
300 ft51 (6 ft)39 (7.89 ft)31 (10 ft)
330 ft56 (6 ft)43 (7.86 ft)34 (10 ft)

Posts, with the actual spacing center to center in brackets, for one straight run with no gates. Length is measured from the center of the first post to the center of the last.

Frequently asked questions

How many fence posts do I need for 100 feet?
14 posts with an 8 ft maximum spacing, 7.69 ft apart. With a 6 ft maximum it is 18 posts 5.88 ft apart, and with 10 ft it is 11 posts 10 ft apart.
How do you calculate fence post spacing?
Divide the length by the maximum spacing, round up to get the sections, and add one post. The posts are then spread evenly: spacing = length ÷ sections. 16 ft at an 8 ft maximum is 2 sections and 3 posts.
How do gates change the number of posts?
The gate openings are taken off the length and the rest is split into equal runs, one more than the gates. 100 ft with two 6 ft gates makes 3 runs of 29.33 ft, each with 4 sections at 7.33 ft: 15 posts, of which 2 are end posts, 4 gate posts and 9 line posts. That assumes evenly placed gates; gates off center can need up to one more post each, so the page also shows the worst case, 17 posts here.
How do I count posts for a fence with corners?
Type the total length of all sides and the number of corners. The corner post is shared by two sides, so it is counted once: two 50 ft sides at an 8 ft maximum are 8 posts each, so 15 posts for the L-shaped fence, and 100 ft with 3 corners (four 25 ft sides) is 17 posts. The tool assumes equal sides; for unequal ones, work out each side on its own, because each side rounds up separately.
What is the gap between fence posts?
The clear gap is the center-to-center spacing minus the post width. For 100 ft at an 8 ft maximum with 4 in posts the posts are 7.69 ft apart and the clear gap is 7.36 ft.
How many bags of concrete do I need for fence posts?
Enter the hole diameter and depth under the post count. For 14 posts in holes 10 in wide and 30 in deep, each hole takes 1.36 cu ft and all 14 take 19.09 cu ft: 51 bags of 50 lb, 43 of 60 lb or 32 of 80 lb. The bag count is the total volume divided by the QUIKRETE Concrete Mix yields (0.375, 0.45 and 0.60 cu ft), rounded up once for the whole job.

Counting posts before you order

It counts the posts for a fence line with gates and corners, and the concrete to set them. Enter the length from the center of the first post to the center of the last, the largest spacing your fence allows and the post width, in imperial or metric units. It splits the posts into end, gate, corner, extra and line posts and gives the sections and the actual spacing. Optional fields add the concrete per hole, extra posts for bracing, rails per section and pickets.

Post count formula

  • sections = ceil(length ÷ maximum spacing)

  • posts = sections + 1

  • actual spacing = length ÷ sections, center to center

  • clear gap = actual spacing − post width

  • concrete per hole = π × (diameter ÷ 2)² × depth

Example: 100 ft at an 8 ft maximum is 12.5, rounded up to 13 sections and 14 posts, 7.69 ft apart, with a clear gap of 7.36 ft between 4 in posts. Holes 10 in wide and 30 in deep take 1.36 cu ft each, 19.09 cu ft for all 14: 51 bags of 50 lb, 43 of 60 lb or 32 of 80 lb, at the QUIKRETE Concrete Mix yields of 0.375, 0.45 and 0.60 cu ft.

Gate openings come off the length and the rest splits into one more run than there are gates: 100 ft with two 6 ft gates is 3 runs of 29.33 ft and 15 posts, 4 of them gate posts. Gates off center can need one more post each; the page shows that worst case.

Each corner adds a run and shares its post between two sides, assumed equal: 100 ft with 3 corners is four 25 ft sides and 17 posts, against 14 for a straight line. Rails are rails per section × sections. Pickets per section are ⌈(clear gap − gap) ÷ (width + gap)⌉: 16 ft at an 8 ft maximum with 3.5 in pickets and 0.5 in gaps is 23 a section.

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