Fence Picket Calculator
Calculate fence pickets, posts, rails, and concrete bags for any fence run. Enter your dimensions and fence style for an instant material estimate.
Fence Run
Post Spacing
8 ft is standard. 6 ft is common for privacy or vinyl fence.
Picket Style
Rails
Gates
Gate openings are excluded from picket and rail count.
Post Concrete
* Picket count includes 10% waste for cuts and damaged boards.
* 1.57 cu ft of concrete per hole - using Quikrete Fast-Set 50 lb bags.
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How to Use the Fence Calculator
Start with total fence length measured along the actual fence line. This is the run or perimeter of the fence, not the square footage of the yard and not the property-line distance unless the fence follows that line exactly.
| Input group | What it controls | Field note |
|---|---|---|
| Fence run | Overall sections, posts, rails, and pickets | Measure along the fence path |
| Post spacing | Number of sections and posts | 8 ft is common, 6 ft is stronger |
| Picket style and gap | Pickets per section | Privacy fences use little or no gap |
| Gates | Openings removed from material count | Do not run pickets or rails through a gate |
| Post concrete | Fast-set bag count | Uses 50 lb bags at 0.375 cu ft each |
Gate openings are important because they reduce the fence run that receives pickets and rails. Enter the gate count and width so the calculator subtracts that open space before it counts boards.
How to Calculate How Many Fence Pickets You Need
Fence estimating starts by turning the fence run into sections. For a straight run, posts sit at both ends, so the post count is one more than the number of sections.
| Worked example | Calculation | Result |
|---|---|---|
| Sections | 100 ft / 8 ft | 12.5, rounded up to 13 sections |
| Posts | 13 sections + 1 | 14 posts |
| Clear span | (8 x 12) - 3.5 | 92.5 inches |
| Pickets per section | floor(92.5 / (3.5 + 0.5)) | 23 pickets |
| Total with waste | ceiling((23 x 13) x 1.10) | 329 pickets |
The calculator uses actual lumber width for a standard 4x4 post, which is 3.5 inches. That detail matters because the clear span between posts is what the pickets fill.
How Much Concrete Do I Need for Fence Posts?
Post concrete is calculated as a round hole. SpecMath uses a 12-inch diameter hole for standard 4x4 and round posts, and an 18-inch diameter hole for 6x6 posts.
| Post size | Hole diameter | Hole depth | 50 lb bags per post |
|---|---|---|---|
| 4x4 post | 12 inches | 2 ft | 5 bags |
| 4x4 post | 12 inches | 3 ft | 7 bags |
| 6x6 post | 18 inches | 2 ft | 10 bags |
| 6x6 post | 18 inches | 3 ft | 15 bags |
The bag count uses Quikrete Fast-Setting Concrete No. 1004 at 0.375 cubic feet per 50 lb bag. SpecMath uses conservative full-hole volume and rounds each hole up to whole bags before multiplying by the number of posts.
Fence Styles and Picket Spacing Reference
Picket width and gap control both the appearance and the material count. Privacy fences use tight spacing, while decorative fences leave more daylight between boards.
| Style | Picket width | Gap | Privacy level | Best for |
|---|---|---|---|---|
| Privacy / solid | 3.5 inches | 0 inches | Full | Backyard privacy, pet containment |
| Standard dog-ear | 3.5 inches | 0.5 inches | High | Most common residential fence |
| Shadowbox | 3.5 inches | 1.75 inches alternate sides | High from straight on | Wind resistance, decorative runs |
| Wide board | 5.5 inches | 0.5 inches | High | Contemporary look, faster install |
| Split rail | No pickets | Open | None | Property boundaries, decorative fences |
Shadowbox fences can use more boards than a simple one-sided privacy fence because boards alternate on both faces. Use the calculator result as a material estimate, then confirm the exact layout with the fence pattern.
Common Fence Calculation Mistakes
Fence takeoffs look simple until small layout details stack up. A few missed posts or bad boards can delay a project even when the overall fence length was measured correctly.
- Not subtracting gate openings from picket and rail count.
- Forgetting that posts go at both ends of a straight run.
- Using nominal lumber size instead of actual 3.5-inch width for a 4x4 post.
- Ordering short posts without checking frost depth and finished fence height.
- Buying the exact picket count with no waste for cuts, knots, or split boards.
A 100-foot fence at 8-foot spacing has 13 sections but 14 posts. That extra end post is easy to miss when estimating quickly from a sketch.
Professional Fence Installation Tips
Professional fence work starts with layout. Set corner and end posts first, pull a string line, then place the line posts so the fence stays straight over the full run.
| Field habit | Why it helps |
|---|---|
| Set corner posts first | Creates stable reference points for the run |
| Let corner concrete cure 24 to 48 hours | Keeps layout from drifting when rails are installed |
| Use a post level | Small errors become obvious across long fence lines |
| Use UC4B ground-contact posts | Posts not rated for ground contact can rot quickly |
| Stage fast-setting concrete before digging | Keeps post setting moving without hand mixing |
Fence Calculator FAQ
How many fence pickets do I need for 100 feet?
For a 100-foot fence using standard 3.5-inch dog-ear pickets with a 0.5-inch gap and 8-foot post spacing, you need approximately 329 pickets including 10% waste. The exact count depends on post spacing, picket width, and gap size. Use the SpecMath Fence Calculator to get the precise number for your layout.
How many posts do I need for a fence?
The number of fence posts equals the number of sections plus one for a straight fence run. Divide total fence length by post spacing to get sections, then add one end post. A 100-foot fence at 8-foot spacing has 13 sections and requires 14 posts.
How deep should fence posts be set?
Fence posts should be set at least one-third of their total length in the ground. A 6-foot tall fence usually needs posts set at least 2 feet deep, and 3 feet is common for stronger work. In cold climates, posts should extend below the local frost line to reduce heaving.
How much concrete do I need per fence post?
A standard 4x4 post in a 12-inch diameter hole at 2 feet deep requires 5 bags of 50 lb Quikrete Fast-Setting Concrete No. 1004 using full-hole volume. A 3-foot deep 4x4 hole requires 7 bags, while a 6x6 post in an 18-inch diameter hole at 3 feet deep requires 15 bags. The calculator rounds each hole up to whole bags so the estimate does not run short.
What is a shadowbox fence?
A shadowbox fence alternates pickets on opposite sides of the rails so the fence looks nearly solid from straight on but allows airflow through angled gaps. This design improves wind resistance while keeping a privacy-fence appearance. It usually requires more pickets than a simple one-sided layout.