Fence Material Calculator — Posts, Rails, and Pickets Estimate
Calculate exactly how many fence posts, rails, pickets, concrete bags, and hardware you need for any fence style and length.
How to Use This Calculator
- Enter the total length of fence in feet (add all sides together)
- Select the fence height and post spacing
- Enter the number of gates and their width
- Adjust the waste factor for cutting and breakage
- Click "Calculate Fence Materials" to see your complete material list
How the Calculation Works
num_posts = ceil(total_length / post_spacing) + 1
num_sections = num_posts - 1 - num_gates
rails_per_section = fence_height <= 4ft ? 2 : 3
total_rails = num_sections × rails_per_section
pickets_per_section = ceil(post_spacing_in / (picket_width_in + gap_in))
total_pickets = pickets_per_section × num_sections × (1 + waste)
concrete_bags_per_post = fence_height <= 4ft ? 1 : 2
total_concrete_bags = num_posts × concrete_bags_per_post Posts are spaced at the chosen interval, with one extra post for the far end. Gate openings subtract from the number of fence sections. Rails are calculated at 2 per section for short fences and 3 for taller fences. Pickets fill the section width at 3.5" nominal width with a small gap. Concrete bags are estimated per post based on fence height.
Variables:
- num_posts: 4×4 posts needed including corners and ends
- num_sections: Panel sections between posts (excluding gate openings)
- total_rails: 2×4 horizontal rails spanning each section
- total_pickets: 1×6 pickets or boards to cover all sections
- total_concrete_bags: Bags of fast-setting concrete for setting posts
Pro Tips
- Set posts at least 1/3 of their total length in the ground (e.g., an 8ft post needs 2.5–3ft underground)
- Dig post holes 6" below the frost line for your area to prevent heaving in winter
- Use fast-setting concrete for posts — no mixing required, just pour dry mix then water
- Always call 811 (Dig Safe) before digging post holes to locate underground utilities
- For 6ft privacy fences, use 4×4 posts with a maximum 8ft spacing to prevent racking
Recommended Products
Frequently Asked Questions
How many posts do I need for a 100-foot fence?
At 8-foot spacing: 100 ÷ 8 = 12.5, rounded up to 13 sections = 14 posts. At 6-foot spacing: 100 ÷ 6 = 16.7, rounded up to 17 sections = 18 posts. Always add posts for corners and gate openings.
How deep should fence posts be set?
The rule of thumb is to bury 1/3 of the post length. For a 6ft fence needing 8ft posts (2ft underground), dig at least 24" deep. In cold climates, go 6" below the frost line to prevent heaving.
How many bags of concrete do I need per fence post?
For a standard 4×4 post, one 50lb or 60lb bag of concrete per post is sufficient for low fences. For 6ft+ fences, use 2 bags per post for added stability. Fast-setting concrete (Quikrete Fast-Setting) is ideal.
What size lumber is used for fence rails?
2×4 pressure-treated lumber is standard for horizontal rails. For taller or heavier fences, 2×6 rails provide more rigidity. Rails should be pressure-treated or rated for ground contact on the lower rail.
How wide are standard fence pickets?
Standard dog-ear fence pickets are 5.5" wide (nominal 6") and come in 3/4" thickness. Gothic-top and flat-top pickets are the same width. For privacy fences, they are typically installed touching or with minimal gap.