Fence Calculator

Build Your Fence Without Over-Buying

Few DIY projects waste more money than a fence ordered by guesswork. Lumber and concrete are heavy, returns are a hassle, and a single missing post can stall a weekend build. This fence calculator turns your property measurements into a precise shopping list: how many posts to set, how many rails to span them, how many pickets to fill the run, and how many bags of concrete to anchor it all. Enter a price per post and you'll also get a quick material cost estimate before you ever load the truck.

The Math Behind a Fence Takeoff

The whole estimate hangs on four simple relationships:

Sections = Total length ÷ Post spacing (rounded up) Posts = Sections + 1 Rails = Sections × Rails per section Pickets = (Length × 12) ÷ (Picket width + Gap)

The "+1" on posts trips people up. A fence is a row of sections, and each section needs a post at both ends — so a 4-section fence has 5 posts, not 4. We round sections up because you can't build a partial bay; a leftover 3 feet still needs its own posts and rails.

A Worked Example: A 120-Foot Backyard Fence

Say you're enclosing a backyard with a 120 ft wood privacy fence, posts every 8 ft, 3 rails per section, 5.5-inch pickets with a 0.5-inch gap.

• Sections: 120 ÷ 8 = 15 sections
• Posts: 15 + 1 = 16 posts
• Rails: 15 × 3 = 45 rails
• Pickets: (120 × 12) ÷ (5.5 + 0.5) = 1,440 ÷ 6 = 240 pickets
• Concrete: 16 posts × 2 bags = 32 bags

At $12 per post, the posts alone run 16 × $12 = $192. That's your skeleton cost before rails, pickets, fasteners and gates — but it's the number that scales fastest if you tighten the spacing.

Why Post Spacing Drives Everything

Notice how spacing controls the entire bill. Drop from 8 ft to 6 ft spacing on that same 120 ft run and sections jump to 20, posts to 21, and concrete to 42 bags — a 30% jump in your two most labor-intensive materials. Wider spacing saves money but sags more, especially with heavy panels or wind exposure. Eight feet is the industry standard because rails and panels ship pre-cut to that length, so you waste almost no lumber.

Practical Tips from the Field

• Set a string line first. Measure the run along the actual fence line, not a straight-line property edge — curves and corners add length.
• Add a 5–10% picket buffer. Boards warp, knots split, and you'll reject a few. The calculator gives you the exact fit; pad it before you order.
• Dig deep enough. Bury at least one-third of each post. A 6 ft fence wants posts in roughly 2 ft holes, which is why two bags of concrete per post is a sound default.
• Account for gates separately. Gate posts carry more load — beef them up to 6x6 and add an extra bag or two of concrete each.

Pair It With Other Estimators

Pouring a footing for a fence, retaining wall, or post pad? Run the volume through our concrete calculator to dial in the exact bag count. Building a masonry boundary wall instead of wood? The brick calculator gives you the same kind of fast material takeoff for block and mortar. Measure once, estimate here, and order with confidence.