Fence Calculator
Estimate posts, rails, pickets, and post-setting concrete for a wood fence - by length, height, and post spacing.
Walk the full perimeter. Gate openings are deducted below - enter the full run here.
How to Use
- Measure total length - walk the perimeter with a tape or measuring wheel; subtract gate openings after.
- Select height - height sets board/post length and the number of rails per section.
- Set post spacing - 8 ft is standard; use 6 ft for tall fences, heavy gates, wind, or hillsides.
- Open Advanced for pickets - set your picket width and gap - 0 gap for solid privacy, ~2 in for spaced pickets.
- Add a price (optional) - enter your cost per linear foot for a material total, or see installed pricing in our Fence Cost Calculator.
A 100 foot privacy fence at 8 foot post spacing is 13 sections when there are no gates: 14 posts, 39 rails for a 6 foot fence, and about 214 pickets at 5-1/2 inch boards with a 1/8 inch gap before waste. When gates are entered, their openings come out of the picket length, but their unknown positions split the fence run. The calculator therefore uses a conservative section/post allowance rather than pretending it knows the gate locations. Concrete is only a rough allowance; use the Post Hole Concrete Calculator with actual hole and post dimensions before ordering.
One Fence Section
Breaking Down Fence Material Quantities
A wood fence is three components: posts, rails, and pickets. Posts anchor every 6 to 8 feet on center - 8 feet is standard for residential privacy fencing and matches pre-built 8-foot panels. Rails run horizontally between posts, with roughly one rail per 24 inches of height (two rails for a 4-foot fence, three for a 6-foot, four for an 8-foot). Pickets attach vertically to form the face.
For a 100-foot privacy fence at 8-foot spacing: 100 ÷ 8 = 13 sections, so 14 posts. At 6 feet tall that's 3 rails per section (39 rails), and with 5.5-inch pickets butted tight, about 218 pickets. Add 10% for waste, cuts, and the occasional crowned board. Gate openings reduce the fenced run and split it into independent sections. Because this calculator does not ask where each gate sits, it uses a conservative extra section and gate-side-post allowance; an exact layout can use fewer when a gate lands on an existing section break.
Planning the installed price instead of the material list? Use our Fence Cost Calculator for installed cost by material, height, and region.
Materials per 100 linear feet by fence style
| Fence style | Posts | Rails | Boards / pickets |
|---|---|---|---|
| 6' wood privacy (8' spacing) | 14 | 39 (3-rail) | ~218 pickets |
| 6' wood privacy (6' spacing) | 18 | 51 (3-rail) | ~218 pickets |
| 4' picket fence (2 in gap) | 14 | 26 (2-rail) | ~160 pickets |
| 8' privacy (8' spacing) | 14 | 52 (4-rail) | ~218 pickets |
| 3-rail split rail | 14 | 39 rails | None |
Counts are before waste and assume no gates. With gates, exact rail/post count depends on gate position. The calculator uses a conservative split-run allowance because gate locations are not entered.
Post depth and concrete by fence height
The table below is a rough planning guide, not a site-specific footing design. Soil, wind, gate loads, local requirements, and post/footing geometry can require different depths or diameters:
| Fence height | Post length | Minimum depth | Hole diameter | Concrete per post |
|---|---|---|---|---|
| 3 ft | 5 ft | 18" | 8" | 1 bag (50 lb) |
| 4 ft | 6 ft | 24" | 8" | 1 bag (50 lb) |
| 6 ft | 8 ft | 24-30" | 10" | 2 bags (50 lb) |
| 8 ft | 10 ft | 30-36" | 12" | 2-3 bags (50 lb) |
Confirm post depth, hole diameter, footing material, frost or heave requirements, and gate-post reinforcement for the actual site. Use the Post Hole Concrete Calculator for concrete volume once those dimensions are known.
Fence calculation formulas
The math behind the counts above:
Base fenced sections = Fenced length ÷ post spacing, rounded up
Planning fenced sections = Base fenced sections + number of gates (conservative split-run allowance)
Planning post count = Planning fenced sections + number of gates + 1
Rails = Planning fenced sections × rails per section (about 1 per 24 in of height, minimum 2)
Pickets = Fenced length (in) ÷ (Picket width + gap)
Concrete bags = Rough allowance from post count and selected fence height; verify with actual hole geometry
With waste = Rails and pickets × (1 + Waste %)
Posts are not multiplied by the waste factor (you order the exact count), but rails and pickets are, to cover cuts and culls. Standard 1×6 cedar dog-ear pickets are 5.5" wide; for board-on-board privacy with no gap, set the gap to 0.
Pickets per 100 Feet by Board Width and Gap
Board width and the gap between pickets set the count. These are per 100 feet of fence, before waste:
| Board width | Gap | Style | Pickets / 100 ft |
|---|---|---|---|
| 5.5 in (1x6) | 0 in | Solid privacy | 219 |
| 5.5 in (1x6) | 1/8 in | Privacy, slight gap | 214 |
| 5.5 in (1x6) | 2 in | Spaced picket | 160 |
| 3.5 in (1x4) | 1 in | Narrow picket, tight | 267 |
| 3.5 in (1x4) | 3 in | Narrow spaced picket | 185 |
| 7.25 in (1x8) | 0 in | Wide solid board | 166 |
Count = fence length in inches divided by (board width + gap), rounded up. A narrower board or tighter gap means more pickets; the calculator applies your exact width and gap, then adds waste.
Installation Note
- Fence post depth and footing requirements are site-specific. Wind exposure, soil, gate loads, frost/heave conditions, fence height, and local rules can change the required post and footing design. Use the calculator as a material-planning estimate, not as a substitute for the project footing requirement.CalcShed planning scope
Related Calculators
Posts need concrete and wood needs finishing - browse the full construction calculator collection.
Frequently Asked Questions
How many fence posts do I need for 200 feet of fencing?
With no gates, 200 feet at 8-foot spacing is 25 sections and 26 posts; at 6-foot spacing it is 34 sections and 35 posts. With gates, exact post count depends on where the openings fall relative to the section spacing. Because gate positions are not inputs, CalcShed uses a conservative split-run allowance so the planning count does not assume ideal gate placement.
How deep should fence posts be set?
A one-third buried-depth rule is a common planning shortcut, not a universal installation requirement. Actual depth can depend on fence height, wind, soil, gate loads, frost/heave conditions, post material, and local rules. Confirm the site requirement before using the concrete allowance as an order quantity.
What is the best post spacing for a privacy fence?
8 feet on center is the residential standard - it matches pre-built 6×8 and 4×8 panels and minimizes post count. Use 6-foot spacing in high-wind zones, on hillsides, or for heavier 8-foot fences. Set the spacing in the calculator to see how it changes your post and concrete counts.
How many pickets do I need?
Divide the fence length in inches by the picket width plus the gap. For 100 feet with 5.5-inch pickets butted tight: (100 × 12) ÷ 5.5 ≈ 218 pickets before waste. Open Advanced options to set your exact picket width and gap - use 0 gap for solid privacy or about 2 inches for a spaced picket fence.
How much does a fence cost to install?
Installed wood privacy fencing typically runs $20 to $45 per linear foot in 2026, depending on material, height, and region. This calculator estimates the material counts; for a full installed-price range by material and height, use our Fence Cost Calculator.
Can I use metal posts with a wood fence?
Yes - galvanized steel posts outlast wood and never rot. They are set the same way, and wood rails attach with brackets. They cost more upfront ($15-$25 vs $8-$15 for treated wood) but eliminate the most common failure point, which is valuable in wet climates where even pressure-treated post bases rot.