How much fencing do you need?
Pick the style, add each run, get pickets, posts, rails and concrete instantly.
How do I calculate how much fence I need?
Measure each straight run of the fence line. Posts go every 8 feet, so a run needs its length ÷ 8, rounded up, sections and one more post than sections. Pickets fill the length: a 100 ft privacy fence with 5½ inch boards touching takes 100 × 12 ÷ 5.5 = 219 pickets, 13 sections and 14 posts.
How many rails does a fence need?
Common practice is two rails per section for a fence up to 4 feet high, three for a 6 ft fence and four for an 8 ft fence, so the boards stay straight. Rails usually match the post spacing — 2 × 4s, 8 feet long, for posts 8 feet apart.
How deep should fence post holes be?
Quikrete recommends a hole three times as wide as the post — about 12 inches for a 4 × 4 — and deep enough for a third of the post, plus 6 inches of gravel at the bottom for drainage; for a 6 ft fence, at least 2 feet. Other guides put one third to one half of the post in the ground, so for an 8 ft post the hole is roughly 2.7 to 4 feet deep. In cold climates, go below the frost line; your local building department knows the frost depth.
How much concrete do I need per fence post?
A 12 inch hole 2 feet deep holds about 1.57 cubic feet; less the 4 × 4 post, about 1.35 cubic feet of concrete — four 50 lb bags of fast-setting mix, which yield 0.375 cubic feet each. The same fence on 14 posts takes about 51 bags. For single holes of other sizes, use the sonotube and post hole calculator.
Pickets or pre-built panels?
Panels go up faster — a 6 by 8 ft panel covers a whole section — but the posts must be exactly one panel apart, so they suit straight, level runs. Building with pickets and rails fits any spacing and slope. Enter prices for both to compare.
Worked example: two runs, 60 and 40 feet
A 6 ft privacy fence has one run of 60 feet and another of 40 feet, with posts 8 feet apart. The 60 ft run needs 8 sections and the 40 ft run 5, 13 in all. Each run has one more post than it has sections, so the posts are 13 + 2 = 15. At three rails per section for a 6 ft fence, that is 39 rails. With 5½ inch boards touching, 100 feet takes 1,200 ÷ 5.5, rounded up, 219 pickets; with ½ inch gaps it takes 200. A 12 inch hole 2 feet deep around a 4 × 4 post holds about 1.35 cubic feet of concrete, so 15 posts need 20.2 cubic feet, or 54 bags of 50 lb fast-setting mix at 0.375 cubic feet per bag.
How long should the posts be?
A post must stand as tall as the fence and also reach to the bottom of its hole, so its length is the fence height plus the hole depth. The calculator adds the two and rounds up to the next standard length of 8, 10 or 12 feet. Guidance on depth differs: Quikrete describes a hole of a third of the post length, or a third to a half of the part above ground, plus 6 inches of gravel at the bottom. Frost depth and local code can require more, so treat the depth field as your own decision.
Why does the post count look high at corners?
Posts are counted for every run on its own, with one more post than sections. Where two runs meet at a corner or a gate, the shared post is counted twice. This is intentional spare: you rarely lose by having one extra post, and gate posts are usually heavier than line posts anyway. Reduce the count by hand if your layout has many shared corners and you want the exact number.
Common fence-estimating mistakes
Measuring the fence in one run when it turns corners, which hides the extra post at each corner. Forgetting that gate openings and their hardware are not part of a picket count. Using the board width as the picket pitch: with gaps the pitch is the board width plus the gap. Measuring along a slope instead of the horizontal run, since panels and rails are laid out on the horizontal distance between posts. Ignoring the post itself in the concrete volume: the hole is not filled where the post stands, which the calculator subtracts.
Sources and related calculators
Sources: Quikrete, setting-posts instructions (hole three times the post width, gravel base, depth guidance) and its fast-setting concrete yield; post counts and rail counts are common practice rather than a code requirement, and local codes govern fence height and post depth. Related: sonotube calculator, concrete calculator, deck footing calculator and mulch calculator.