Fence length in, full materials list out — posts, rails, pickets, concrete bags and a priced total, with gates and corners taken off the run.
Construction
Post holes & concrete
Prices (optional)
Posts needed
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Fence sections—
Fenced length (gates removed)—
Rails—
Rail linear length—
Pickets—
Post length to buy—
Concrete bags—
Estimated material cost—
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How the counts come out
Sections = fenced length ÷ post spacing, rounded up. Posts = sections + 1 for a straight run, plus one extra for every corner and every gate, since a gate needs a post on both sides.
Rails = sections × rails per section. Three rails is standard for a 6 ft privacy fence — top, middle and bottom. Two is enough below about 5 ft; go to four above 7 ft or the pickets will cup.
Pickets = fenced length in inches ÷ (picket width + gap). A gap of zero gives a solid privacy fence; a gap equal to the picket width gives a classic 50% open picket fence; a shadowbox alternates sides and needs roughly double the pickets.
Post depth: the rule that matters most
Bury one third of the total post length, or a minimum of 24 inches — whichever is deeper — and always below your local frost line. A 6 ft fence therefore wants an 8 or 9 ft post with 24–30 inches in the ground. Skimping here is the single biggest cause of fences leaning within a few seasons, and it cannot be fixed afterwards without pulling everything.
Concrete per hole
Hole volume is π × radius² × depth, less the volume the post itself occupies. A 10 inch hole 30 inches deep with a 4×4 post takes about 1.1 ft³ — roughly two 80 lb bags. A good rule of thumb is that the hole diameter should be about three times the post width.
Fences are built from the corners in, not from one end along. Set and plumb every corner, end and gate post first, run a string line between them, then space the line posts evenly along that string. Working end-to-end means every small error accumulates, and you finish with an awkward 3 ft section at the far corner. Spacing does not have to be exactly 8 ft — it has to be equal, and slightly under 8 ft is better than slightly over.
Gates, ground and wood movement
Gate posts carry a swinging load and should be a size up from the line posts, set deeper, and concreted generously. Leave about ½ inch of hinge-side clearance and ¾ inch on the latch side.
On sloping ground you can either rack the fence, following the grade with parallel rails, or step it, keeping each section level and dropping between posts. Racking suits gentle slopes and pickets; stepping suits prefabricated panels but leaves triangular gaps at the bottom. Either way order 5–10% extra pickets — pressure-treated lumber arrives wet, shrinks as it dries, and some boards will be too warped to use.
At 8 ft spacing, 100 ft needs 13 sections, so 14 posts for a straight run — plus one extra for each corner and one extra per gate. Corners and gate posts should also be set deeper than line posts.
How far apart should fence posts be?
Six to eight feet is standard, with 8 ft the most common because rails come in 8 ft lengths. Use 6 ft for tall fences, heavy panels or windy sites. Equal spacing matters more than hitting an exact number.
How deep should fence posts be?
One third of the total post length or 24 inches, whichever is more, and always below the frost line in your area. A 6 ft fence typically needs 24 to 30 inches of post in the ground, which means buying 8 ft posts.
How many bags of concrete per fence post?
Roughly two 80 lb bags for a typical 10 inch wide, 30 inch deep hole with a 4×4 post. Wider or deeper holes and corner posts need more — the exact figure for your hole size is calculated above.
How many pickets do I need for a 6 foot fence?
Divide the fenced length in inches by the picket width plus the gap. With 5½ inch boards butted tight, 100 ft of solid fence takes about 219 pickets; with a ½ inch gap it drops to about 200. Order 5–10% extra for warped boards.