Fencing Calculator
Calculate posts, rails, pickets, and materials for your fence project.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Fencing Calculator
This calculator gives you a complete material list for a wood privacy or picket fence based on your perimeter length and style preferences. Here is how to use it:
- Enter total fence length. Measure the full perimeter you want to enclose in feet. If you are fencing three sides of a yard, add those three measurements together. This is the total linear footage of fence line.
- Set fence height. Standard privacy fences are 6 ft. Shorter decorative fences are typically 3-4 ft. This affects material selection and rail count but does not directly change the picket count formula, which is driven by linear length.
- Choose post spacing. The default is 8 ft on center, which is standard for 8-ft fence boards purchased from a lumber yard. You can use 6 ft spacing for extra strength or on uneven terrain. The calculator adds one extra post for the end.
- Select rails per section. Use 2 rails for fences up to 6 ft. Use 3 rails for fences over 6 ft or for added rigidity on longer spans.
- Set picket width and gap. Standard fence boards are 3.5 inches wide (a nominal 1x4). Set gap to 0 for a solid privacy fence. For a shadowbox or spaced picket fence, set a gap of 0.25 to 0.5 inches.
- Enter gates. Each gate opening subtracts that width from the picketed fence length. Gate posts and hardware are not included in the picket or rail count for those spans.
Results update instantly as you type. Use the Share button to send your estimate to a contractor or co-owner, or Copy to paste it into your materials list.
About the Fencing Calculator
Building a fence involves four main material categories: posts, rails (also called stringers), pickets or boards, and post-hole concrete. Each is calculated differently. Posts are spaced at regular intervals along the fence line, with one extra post at the end of the run. Rails span between posts in horizontal rows, one per side per section. Pickets attach vertically to the rails and cover the linear footage at a rate determined by their width plus any spacing gap.
Post holes are set in concrete to keep posts plumb and prevent heaving. The standard recommendation is two 50-lb bags of fast-setting concrete per post for posts set 2-3 ft deep. For larger diameter posts or deeper holes, you may need more. This calculator uses 2 bags as the default and does not account for post diameter or soil type, so treat the concrete estimate as a minimum baseline.
All calculations run in your browser. No data is sent to any server.
Frequently Asked Questions
How do I calculate how many fence posts I need?
Divide the total fence length by your post spacing, round up to the nearest whole number, then add 1 for the terminal post at the end of the run. For example, a 100-foot fence with 8-foot spacing needs ceil(100/8) + 1 = 13 + 1 = 14 posts. If your fence turns corners, each corner also needs a post, and you may need to count that post in multiple runs to avoid double-counting.
How many pickets do I need per linear foot?
For a standard privacy fence with 3.5-inch wide boards and no gap, you need ceil(12 / 3.5) = 4 pickets per linear foot, or about 343 pickets for 100 linear feet. If you add a 0.25-inch gap between boards, each slot becomes 3.75 inches, reducing the count to ceil(100 * 12 / 3.75) = 320. The formula is: pickets = ceil(total length in inches / picket slot width in inches).
How much concrete do I need for fence posts?
The standard recommendation is 2 bags of 50-lb fast-setting concrete per post. This is suitable for a 4x4 post set 2 feet deep in a standard hole. For a 4x4 post set 3 feet deep, you may need 3 bags. For larger 6x6 posts, budget 3-4 bags per post. This calculator uses the 2-bag default. Always buy an extra bag or two as a buffer since soil conditions vary.
Should I use 2 rails or 3 rails per fence section?
For fences up to 6 feet tall, 2 rails are standard: one near the top and one near the bottom. For fences over 6 feet, or for any fence where you want extra rigidity, add a third rail in the middle. A 3-rail configuration also reduces bow and warping over time on long spans. Most pre-built fence panels use 3 rails. If you are building a shadowbox fence, 3 rails are typically required to offset the alternating boards correctly.