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 the standard 8 foot post spacing is 13 sections: 14 posts, 39 rails for a 6 foot fence (3 per section), and about 214 pickets at 5-1/2 inch boards with a 1/8 inch gap - roughly 43 rails and 235 pickets once you add 10 percent waste. Set 9 foot posts 3 feet deep, two 50-pound bags of concrete each. Gate openings come off the rails and pickets but not the posts, since you still need a post on each side. Enter your fence length above for the full bill of materials.
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 add two posts each and need bracing - count them on top of the line posts above.
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 5.5-inch pickets butted tight; the calculator above adds your selected waste % to rails and pickets. Add two posts per gate.
Post depth and concrete by fence height
Post depth should be at least one-third of total post length. In cold climates, posts must go below the frost line regardless:
| 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) |
In northern states, frost lines reach 30-48 inches - always dig below your local frost depth or posts will heave. Set corner, end, and gate posts in concrete; line posts can be set in compacted gravel if soil is stable.
Fence calculation formulas
The math behind the counts above:
Post count = Sections + 1
Rails = Sections × rails per section (≈ 1 per 24" of height, min 2)
Pickets = Total length (in) ÷ (Picket width + Gap)
Concrete bags = Post count × bags per post (see table above)
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.
Code Note
- Fences have no prescriptive material section in the residential code, but the footing frost-depth rule applies to anything set in the ground: in cold regions the post holes must reach below the local frost line - commonly 24 to 48 inches - or the posts heave over winter even when concreted. Confirm your frost depth with the local building department.IRC 2021 Section R403.1 - Footing Frost Depth
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?
At standard 8-foot spacing: 200 ÷ 8 = 25 sections, so 26 posts. At 6-foot spacing: 200 ÷ 6 = 34 sections, so 35 posts. The calculator always adds one for the starting end post. Gate openings need two posts each, separate from the line-post count.
How deep should fence posts be set?
The rule is one-third of total post length in the ground. A 6-foot privacy fence uses 8-foot posts with about 2 feet buried. In cold climates, posts must go below the frost line - from 12 inches in the South to 48 inches in the far North. Setting posts at frost depth prevents heaving, even when concreted.
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.