Short answer
A 150-foot fence using 5½-inch pickets with a ½-inch gap requires 300 pickets. You'll also need 20 posts, 19 rail boards, and 40 bags of 60 lb fast-setting concrete. These are exact counts — add a 5% waste factor (15 pickets) for a real order.
How this calculator works
The core calculation is straightforward division. Every picket takes up a fixed amount of horizontal space: its own width plus the gap you leave before the next one. For standard dog-ear cedar, that's 5½ inches of board plus ½ inch of air — 6 inches per picket. Your 150-foot fence is 1,800 inches long. Divide 1,800 by 6 and you get exactly 300 pickets.
Written as a formula: ceil((fence_length_ft × 12) ÷ (picket_width_in + gap_in))
The ceil() function rounds up to the nearest whole number, because you can't buy a fraction of a picket. If your fence length didn't divide evenly, you'd still need one more full board to finish the last section.
Inputs and what they mean
- Fence length (ft): The total linear footage of fence line, corner to corner, not counting gate openings. Measure along the ground, not diagonally.
- Picket width (in): The face width of the board, not the thickness. Standard dog-ear and flat-top cedar pickets sold as "5½ inch" actually measure 5½ inches — no nominal vs. actual surprise here like you get with dimensional lumber.
- Gap between pickets (in): For a privacy fence, ½ inch is standard. This allows the wood to expand in wet weather without buckling. If you want zero gap (solid tight-board), enter 0 — the board count goes up to 328 for this same 150-foot run.
Secondary outputs explained
The calculator also generates a full materials list for the fence structure itself:
- Posts: Spaced every 8 feet, plus one endpoint post. For 150 feet:
ceil(150 ÷ 8) + 1 = 19 + 1 = 20 posts. The last bay will be slightly less than 8 feet — that's normal and preferable to forcing an exact span. - Rails: Using 16-foot boards with two rails per bay (top and bottom), you need
ceil((150 × 2) ÷ 16) = 19 boards. Many contractors add a third center rail on 6-foot privacy fences; if you do that, multiply the rail count by 1.5 and round up. - Concrete: Two 60 lb bags per post hole for a 4×4 post sunk 24–30 inches. That's
20 posts × 2 = 40 bags. Fast-setting concrete lets you set the post plumb and move on in 20–40 minutes without mixing in a bucket. - Linear feet of pickets: The calculator reports 150 linear feet of picket material — which makes sense here because 300 pickets × 6 inches each = 1,800 inches = 150 feet. This figure is useful when ordering by the bundle or pallet.
Waste factor
The raw formula gives you the minimum count. A 5% waste allowance covers the boards you'll reject at the lumber yard for bad knots, the ones that split when you nail them, and the off-cuts at gates and corners. For 300 pickets, 5% adds 15 boards — budget for 315 if you're ordering from a single delivery.
What this calculator doesn't cover
Corner posts, gate hardware, post caps, and fasteners aren't in the output. For hardware, a rough rule is 3 ring-shank nails or screws per picket per rail — for a two-rail fence with 300 pickets, that's 1,800 fasteners minimum.
Common mistakes and gotchas
Recommended materials
Cedar is the go-to species for residential privacy fences because it's naturally resistant to rot and insects without chemical treatment. Pressure-treated posts and rails are the standard framing material even when the pickets are cedar — ground contact demands the extra protection. For a 150-foot fence, plan for one pallet of pickets, a truck-load of posts and rails, and a half-pallet of concrete.
- Cedar dog-ear picket 5/8 in x 5-1/2 in x 6 ft — the standard residential privacy picket; buy by the bundle of 5 or pallet of 200+
- Pressure-treated 4x4 in x 8 ft fence post — UC4B ground-contact rating; what you need for post holes
- Pressure-treated 2x4 in x 16 ft fence rail — 16-foot stock minimizes joints; spans two bays per board
- Quikrete fast-setting concrete (60 lb bag) — pour dry into the hole, add water, done; no mixing required
FAQ
How many fence pickets do I need for 150 feet? With standard 5½-inch-wide pickets and a ½-inch gap, you need exactly 300 pickets. That assumes no waste — add 5% (15 extra pickets) to cover splits, bad knots, and cut-offs at corners.
How many fence posts do I need for a 150-foot fence? At 8-foot spacing, you need 20 posts. That includes the two endpoints and every post in between, with the last section potentially running slightly shorter than 8 feet.
How many rails do I need for a 150-foot fence? Using 16-foot rail stock at two rails per section (top and bottom), you need 19 boards. Most installers run a third mid-rail on 6-foot privacy fences to prevent warping.
How many bags of concrete for 150-foot fence posts? At 2 bags of 60 lb fast-setting concrete per post hole, 20 posts requires 40 bags. This assumes holes are roughly 10 inches in diameter and 24–30 inches deep.
What gap should I leave between fence pickets? A ½-inch gap is the standard for a traditional privacy fence — it allows slight board movement as wood expands and contracts without leaving a visible gap when viewed straight-on. Zero gap is fine for true tight-board privacy but requires kiln-dried lumber.
Does the calculator account for waste? The base formula gives you the exact count with no waste. The calculator applies a 5% waste factor on top of that, which covers typical defects in a cedar or pressure-treated picket order. On a 300-picket job that's 15 extra pickets.
What is the formula for calculating fence pickets? Divide the total fence length in inches by the sum of picket width plus gap width. For 150 feet: (150 × 12) ÷ (5.5 + 0.5) = 1800 ÷ 6 = 300 pickets.
Are dog-ear and flat-top pickets the same width? Yes — the profile (dog-ear vs. flat-top vs. Gothic) is the top cut only. The board width is the same, so the count calculation doesn't change based on picket style.
Can I use this calculation for a shadowbox (board-on-board) fence? No. Shadowbox fences overlap alternating pickets on opposite sides of the rail, which requires roughly 60–70% more pickets than a standard privacy fence. You need a separate calculation for that layout.
What wood species is best for backyard fence pickets? Western red cedar is the most popular choice for its natural rot resistance and light weight. Pressure-treated pine costs less upfront and accepts stain well, but it's heavier and takes a full season to dry before painting.
Should I account for the gate when calculating pickets? Yes. Subtract any gate opening widths from your total fence length before calculating. A 4-foot gate in a 150-foot perimeter means you're only buying pickets for 146 feet, not 150.
How does corner treatment affect the picket count? Inside and outside corners each require a post, which is already factored in at 8-foot spacing. The picket count itself doesn't change at corners — you just cut the last picket to fit against the corner post like any other end.