Fence Calculator — Posts, Pickets & Concrete

At 8 ft spacing with one gate and no corners, 150 ft of fence needs 21 posts. Every corner adds one more that this length-based count cannot see on its own — enter your actual corner count above for the exact number.

8 feet is standard for wood privacy and picket fence, and it is the default here. Chain link runs to 10 ft between line posts per CLFMI, and taller or heavier panel styles sometimes call for 6 ft to keep the panel from racking. Check your specific fence style — closer spacing means more posts but a stiffer, straighter line.

For a solid privacy fence with 5.5" (1×6) pickets butted tight, an 8 ft section takes about 17 pickets (96" ÷ 5.5" = 17.5, rounded up). A spaced picket fence with an equal gap takes roughly half that. The calculator above gives the exact count for your picket width and gap.

At the standard 8 ft spacing, 100 ft of fence is 13 sections, which needs 14 posts — sections plus one, because a run has a post at both ends. Then add one extra post per gate and one per corner.

The corner point is the one that catches people. A length-based formula cannot see corners: 100 ft of fence around a rectangular yard needs the same 14 posts plus one at every direction change. Count them off the plan and enter them separately.

The rule of thumb is one third of the above-grade height, or the local frost depth, whichever is deeper. A 6 ft fence gives 2 ft by the one-third rule, so an 8 ft post.

But frost depth overrides it and varies enormously — from zero in southern Florida to 8 ft in northern Minnesota. A post set above the frost line will heave, and once a fence line has heaved unevenly it never comes back. Your building department publishes the local figure; use it.

For a 4×4 post in a 12" hole 2 ft deep, about 1.03 cubic feet after subtracting the post — roughly two 80 lb bags. The hole diameter should be about three times the post width.

Subtracting the post matters more than it sounds. A 4×4 is actually 3.5" square and occupies 13% of a 12" hole; a 6×6 occupies nearly 30%. Over the 16 posts in this example that is several bags, and most calculators quote the full hole volume.

Divide the fence length by the picket pitch — the picket width plus the gap between pickets. For a solid privacy fence the gap is zero, so a 5.5" (1×6) picket gives 5.5" of fence per picket: 100 ft needs about 218 before waste.

For a spaced picket fence the gap is usually equal to the picket width, which halves the count. Use the actual dressed width, not the nominal: a 1×6 is 5.5" wide, not 6", and using 6" under-orders by 9%.

Frequently, yes — and almost always above 6 ft. Many jurisdictions cap residential fence height outright, restrict height in front-yard setbacks to 3 or 4 ft, and have rules about which side the finished face must point.

HOA covenants are separate from and often stricter than the zoning ordinance. Check both before buying material, and confirm your property line with a survey rather than the existing fence, which is frequently in the wrong place.

Concrete is standard and gives the most rigid result, but it holds water against the post if the hole has no drainage. The usual compromise is a few inches of gravel in the bottom of the hole, concrete around the post, and the concrete crowned above grade so water sheds away rather than pooling at the base.

Gravel-only setting drains better and is much easier to remove later, but it gives a less rigid fence and is not appropriate for gate posts, which take real cyclic load every time the gate swings.