How Many Fence Posts Do I Need?

Divide your fence's length by your post spacing (8 ft on-center is standard), round up to a whole section, then add one — a fence always needs one more post than it has sections. That covers a single straight run; for corners, gates, or a different picket size, the fence calculator handles those directly. This page is a quick reference table by fence length, plus a worked example for a fence with a corner.

Posts, rails, and pickets by fence length

Figures below assume 8 ft post spacing, a tall (6 ft+) privacy fence at 3 rails per section, and standard 5.5in pickets with a 0.25in gap.

Post spacing default (8 ft on-center): This Old House, "How to Build a Fence" — a shorter fence (up to about 4 ft) needs fewer rails per section, which changes the rail column but not posts or pickets; the calculator switches height categories directly.

A full example: an L-shaped fence with one corner

This calculator models one straight run, and a corner means two runs sharing one post — a common source of over-ordering if you calculate each run in isolation and simply add the results. Take an L-shaped yard fence: a 60 ft run and a 40 ft run meeting at one corner, both tall privacy height. The 60 ft run needs 60 ÷ 8 = 7.5, rounded up to 8 sections, or 9 posts; 8 sections × 3 rails = 24 rails; and 60 ft = 720 in ÷ 5.75in per picket unit ≈ 125.2, rounded up to 126 pickets. The 40 ft run needs 40 ÷ 8 = 5 sections exactly, or 6 posts; 5 × 3 = 15 rails; and 40 ft = 480 in ÷ 5.75in ≈ 83.5, rounded up to 84 pickets. Adding the two runs separately gives 9 + 6 = 15 posts — but the corner post is shared between both runs, not built twice, so the real total is 14 posts, along with 24 + 15 = 39 rails and 126 + 84 = 210 pickets. Missing that one-post correction is a small error on a two-run fence, but it compounds on a yard with three or four corners.

How post spacing changes the count

The table above uses 8ft spacing, the upper end of the 6–8 ft range that fence-building guides cite for residential wood fences. Many tall privacy fences are built closer than that, and the post count climbs faster than most people expect, because every foot you take off the spacing adds sections along the whole run:

On a 200 ft run, moving from 8 ft to 6 ft spacing adds nine posts, and each of those is a hole to dig and set, plus another section of rails to buy. Spacing also decides how well your rails fit standard lumber. Rails are usually cut from 8, 10, 12, or 16 ft boards. At 8 ft spacing an 8 ft rail spans one section with nothing left over; at 6 ft spacing, a 12 ft board covers two sections with no offcut, while an 8 ft board wastes 2 ft per rail. Choosing the spacing and the rail length together keeps the scrap pile small.

Uneven runs: space the posts evenly

When a run doesn't divide cleanly by your spacing, the count still rounds up to a whole section, but you don't have to build seven full sections and one short one. In the example above, the 60 ft run needs 8 sections either way. Spread those 8 sections evenly and each one is 60 ÷ 8 = 7.5 ft on-center instead of seven at 8 ft and a leftover 4 ft stub. The post count, rail count, and picket count don't change, but every rail is the same length, the fence looks uniform from the street, and the short, weak-looking section at the end disappears. The same idea works on a long run with a gate: lay out the gate opening first, then divide each remaining stretch into equal sections.

A fully enclosed yard

A fence that closes on itself has no free ends, so the "one more post than sections" rule turns into "one post per section." Take a 60 × 40 ft backyard fenced on all four sides. The two 60 ft sides need 8 sections each and the two 40 ft sides need 5 sections each, for 26 sections. Calculated as four separate runs, that's 9 + 6 + 9 + 6 = 30 posts, but each of the four corners is shared by two runs, so the real count is 30 − 4 = 26 posts, the same as the section count. If one side of the yard is the back wall of the house instead, the fence becomes a U-shaped run with two free ends that attach to the house. There, each run is calculated alone and one post is subtracted per shared corner, as in the L-shaped example above. Then check whether the two ends against the house will be real posts or brackets fixed to the wall.

Measuring mistakes that change the post count

The most common error is measuring the yard instead of the fence line. A fence usually sits a few inches to a few feet inside the property line to meet local setback rules, and that shortens each run. Measuring the lot dimensions from a plat and entering them directly can add a section per side. The second error is rounding each run's length before dividing. Treating a 65 ft run as 64 ft to make the math tidy drops it from 9 sections to 8, leaving a gap you won't find until the last section. Measure each run to the nearest foot, round only the section count, and keep a written list of runs so shared corners are easy to count.

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