Fence Calculator
Pickets, posts, and rails for a privacy fence from length and picket size.
What it does
A privacy fence is mostly picket arithmetic with posts at fixed steps. Total run length in inches divided by each picket plus its gap gives the board count, and posts land at every section break plus both ends. Rails tie it together, two per section for standard heights.
The tool above runs that takeoff from length, picket width, gap, and spacing. It returns picket and post counts, rail boards, and picket cost at your price.
Ground contact decides post life. Set posts a third of the exposed height deep, crown concrete away from the wood, and keep picket bottoms two inches off the soil. Most leaning fences trace back to shallow or rotted posts, not weak pickets.
Wind and height change the build. Six foot privacy in open ground wants three rails and deeper posts, while short picket or spaced designs stay light with two.
How to use
- Switch the unit system first: imperial for feet and inches, metric for meters and centimeters.
- Measure the run in feet and subtract gate openings.
- Enter actual picket width and the gap. Zero gap means privacy.
- Set post spacing, usually 8 ft, and rails per section.
- Buy the counts plus five percent spares, with concrete per post.
Formula
- length in inches
- Run length times 12. Gates come out before dividing.
- picket + gap
- Inches each board consumes along the run.
- spacing
- Feet between posts. Eight is standard for wood privacy.
- plus one post
- Both ends need a post, so sections plus one.
Boards vary in width by an eighth inch or more, which is why the tool rounds up and spares cover the drift. On slopes, step sections level and add length for the stair effect.
Worked example
Example: 100 ft run, 5.5 in pickets, no gap, 8 ft posts
Length 100, pickets 5.5 in wide touching, posts every 8 ft, 2 rails, $3.50 per picket.
- Inches: 100 x 12 = 1200.
- Pickets: 1200 / 5.5 = 218.2, round up to 219.
- Sections: 100 / 8 = 12.5, round up to 13.
- Posts: 13 + 1 = 14, each with a bag or two of concrete.
- Rails: 13 sections x 2 = 26 eight-foot rails.
- Pickets cost: 219 x $3.50 = $766.50 before posts, rails, and concrete.
Reference table
| Picket | Boards per section | Per 100 ft |
|---|---|---|
| 1x4 (3.5 in) | 28 | 343 |
| 1x6 (5.5 in) | 18 | 219 |
| 1x8 (7.25 in) | 14 | 166 |
| With 0.5 in gap, 1x6 | 16 | 200 |
Limits
- Straight runs only. Corners need extra posts and bracing.
- Slopes add length and steps that the flat math misses.
- Gates, hardware, stain, and concrete sit outside picket cost.
- Picket widths vary, so counts are estimates plus spares.
Common mistakes
- Forgetting gate openings, then cutting pickets to fit.
- Setting posts shallow. A third of exposed height underground is the rule.
- Burying pickets in soil contact, which rots bottoms in a few seasons.
- Skipping the string line, so the run waves.
- Buying exact pickets with zero spares for crooked boards.
Try it yourself
Quick checks. Answers sit tucked under each question.
A 48 ft run with 5.5 in pickets, no gap. How many?
48 x 12 = 576 inches. 576 / 5.5 = 104.7, so 105 pickets.
Posts for a 64 ft run at 8 ft spacing?
64 / 8 = 8 sections, plus one end post: 9 posts.
Questions
How deep should fence posts go?
About a third of the exposed height: 2 ft for a 6 ft fence, deeper in frost or wind zones, set in concrete or compacted gravel.
How many rails for a 6 ft fence?
Two for sheltered runs, three for tall, heavy, or windy builds. Space them evenly with one near top and bottom.
Should pickets touch the ground?
No. Hold them about 2 inches up so bottoms dry between rains.
How much gap for semi privacy?
About half an inch to an inch. It reads solid from an angle while venting wind.
How many pickets per 8 ft section?
At 5.5 in with no gap, 96 / 5.5 = 17.5, so 18 pickets per section.
Do I need a permit?
Often for tall or front yard fences. Check local height and setback rules before digging, and call utility marking first.