Fence Calculator: Posts, Rails & Materials Estimator Guide

Planning a fence project requires accurate material calculations to avoid costly delays and wasted materials. Whether you're installing a privacy fence, picket fence, or split rail, knowing exactly how many posts, rails, and pickets you need is essential. Our fence calculator handles these calculations automatically.

The key to fence calculation is understanding post spacing, rail requirements, and picket coverage. This guide covers the standard formulas and considerations for wood, vinyl, and chain link fencing.

Calculating Posts

Number of Posts = (Total Length ÷ Post Spacing) + 1

Standard post spacing is 8 feet for most fences, though 6 feet is recommended for tall privacy fences or high-wind areas.

For a 100-foot fence with 8-foot spacing: (100 ÷ 8) + 1 = 13.5 → 14 posts

Corner posts and gate posts are additional - add 2 posts per gate.

Calculating Rails

Most fences use 2-3 horizontal rails:

• 4-foot fence: 2 rails (top and bottom)
• 6-foot fence: 3 rails (top, middle, bottom)
• 8-foot fence: 3-4 rails

Number of Rails = (Total Length ÷ Rail Length) × Number of Horizontal Rails

With 8-foot rails for a 100-foot, 6-foot tall fence: (100 ÷ 8) × 3 = 37.5 → 38 rails

Calculating Pickets

Picket calculation depends on width and spacing:

Pickets = Total Length × 12 ÷ (Picket Width + Gap)

For 3.5-inch pickets with 1.5-inch gaps: picket + gap = 5 inches

For a 100-foot fence: 100 × 12 ÷ 5 = 240 pickets

For privacy fences with no gap: 100 × 12 ÷ 3.5 = 343 pickets

Post Hole Concrete

Each post typically needs 1-2 bags of concrete (50 lb bags) depending on hole depth:

• 4-foot fence: 18" deep hole, 1 bag per post
• 6-foot fence: 24" deep hole, 1.5 bags per post
• 8-foot fence: 30" deep hole, 2 bags per post

Typical Fence Costs (2026)

• Wood privacy fence: $20-35 per linear foot (materials)
• Vinyl fence: $25-45 per linear foot (materials)
• Chain link: $10-20 per linear foot (materials)
• Professional installation: adds $15-25 per linear foot

Frequently Asked Questions

How far apart should fence posts be?

Standard spacing is 8 feet for most fences, 6 feet for tall privacy fences or windy areas. Never exceed 8 feet or the fence will sag over time.

How deep should fence posts be?

Posts should be buried 1/3 of their total length. A 6-foot fence with 8-foot posts needs posts buried 2 feet deep. In frost-prone areas, posts should extend below the frost line.

How much concrete per fence post?

Plan for 1-2 bags (50 lb) per post, depending on hole diameter and depth. Use our concrete calculator for precise amounts.