Fence Calculator
Building a new wood privacy fence or property perimeter? Our free fence calculator computes exact counts for 4x4 posts, 2x4 horizontal rails, vertical pickets, gate posts, and bags of fast-setting post concrete.
Project Inputs
Enter your measurements to calculate exact materials
Enter measurements above to view calculation results.
Step-by-Step Calculation Example
Scenario: Building a 100 ft long, 6 ft high wood privacy fence with 8 ft post spacing and 1 gate.
Calculate Sections: 100 ft ÷ 8 ft = 12.5 -> 13 bays.
Calculate Posts: 13 + 1 + 1 (gate post) = 15 posts.
Calculate Rails (3 per bay): 13 bays × 3 rails = 39 rails (2x4x8).
Calculate Pickets: (100 ft × 12 in) = 1200 in - 36 in (gate) = 1164 in ÷ 5.5 in/picket = 211.6 + 5% buffer = 223 pickets.
Calculate Concrete: 15 posts × 2 bags = 30 bags.
Fence Materials Formula
Posts = ⌈ Length ÷ Spacing ⌉ + 1 + Gates; Pickets = ⌈ (Length × 12) ÷ Board Width ⌉ × 1.05 Dividing total length by post spacing gives the number of fence bays. Adding 1 yields line posts. Horizontal rails are computed as rails per bay (3 rails for 6ft fences). Picket counts divide net fence length by picket width plus 5% scrap buffer.
Formula Variables
Calculation Assumptions
- Fence posts are buried at least 1/3 of total height in ground with 2 bags of concrete per post hole.
- 6ft privacy fences require 3 horizontal rails (top, middle, bottom) to prevent board warping.
Frequently Asked Questions
Common homeowner and DIY questionsFence Calculator
How deep should fence post holes be?
Post holes should be dug to at least 1/3 to 1/2 of the above-ground post height. For a 6-foot fence, dig 24 to 30 inches deep (or below your local winter frost line).
How many bags of concrete do I need per fence post?
Plan for two (2) 50 lb bags of fast-setting concrete per standard 4x4 post hole. For gate posts and corner posts carrying extra tension, use 3 bags.
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