🚧 Professional Fence Calculator PRO

Formulas

Posts= Total Length ÷ Post Spacing + 1

Post Hole Depth= Fence Height ÷ 3 + Frost Line + 6" gravel base

Concrete per Hole= π × (Tube Radius)² × Hole Depth

Rails= (Posts - 1) × Rails per Section

Pickets (Standard)= (Post Spacing × 12) ÷ (Picket Width + Gap) × Sections

Pickets (Shadowbox)= Standard × 1.5 (double-sided staggered)

Pickets (Board-on-Board)= Standard × 2 (overlapping boards)

Frost Line by Region (US)

• 12" — Southern states (FL, TX, LA, MS, AL, SC, GA)
• 18" — Mid-South (NC, TN, OK, AR, NM, AZ)
• 24" — Mid-Atlantic, Central (VA, MO, KS, CO, UT)
• 36" — Northern (PA, OH, IL, IN, IA, NE)
• 42"+ — New England, Upper Midwest (NY, MA, MN, WI, MI, MT)

Material Comparison

• Pressure-Treated Pine — Most affordable, 15-20yr life, requires staining
• Cedar — Naturally rot-resistant, lighter, 20-25yr life
• Redwood — Premium, most rot-resistant, 25-30yr life
• Vinyl — Zero maintenance, 20-30yr, can become brittle in cold
• Composite — Recycled wood/plastic blend, 25-30yr, eco-friendly
• Chain Link — Budget option, 15-20yr, no privacy
• Wrought Iron — Elegant, requires painting, 20-30yr
• Aluminum — Lightweight, rust-proof, 20-30yr, good for pool fencing

Worked Example

100 ft Cedar Privacy fence, 6 ft tall, 8 ft post spacing, 5.5" pickets, 36" frost line:

• Posts: 100 ÷ 8 + 1 = 14 posts
• Hole depth: 6ft ÷ 3 + 36" + 6" = 66" (5.5 ft deep)
• Concrete per hole (10" tube): π × 5² × 66 = 5,184 in³ = 0.1 yd³
• Rails: 13 × 3 = 39 rails
• Pickets: (8 × 12) ÷ (5.5 + 0.5) = 16 per section × 13 = 208 pickets
• Gravel base: 14 × 1 bag = 14 bags
• Post caps:14 caps

Pool Code Requirements (IRC R326)

• Minimum height: 48 inches from grade
• No climbable features within 18" of ground
• Gate must beself-closing and self-latching
• Latch release must be 54"+ above grade
• No gaps allowing a 4" sphere to pass through

Common Mistakes to Avoid

• Not calling 811 for utility locating before digging
• Setting posts in dirt without gravel base (rot risk)
• Ignoring frost line — posts will heave in winter
• Using standard lumber for ground contact (use pressure-treated rated for ground contact)
• Forgetting gate posts need to be 4×6 or 6×6, not 4×4
• Not allowing concrete to cure 24-48 hours before attaching rails
• Spacing pickets too far apart — measure twice, cut once

Professional Tips

• Use 4×4 posts for up to 6 ft fence; 6×6 for taller or gate posts
• Set posts ⅓ of their total length below ground
• Place 4-6" of gravel at the bottom of each hole for drainage
• Use post brackets instead of direct burial for easier replacement
• Stain or seal wood fences within 6 months of installation
• Pre-drill screw holes in cedar and redwood to prevent splitting