Deck & Fence Calculators

Building a deck or fence is one of the most impactful outdoor projects you can take on — and one of the easiest to under-estimate when it comes to materials. A fence is not just pickets; it is posts, rails, concrete for every post hole, screws or nails, and often a gate kit or two. A deck is not just boards; it is joists, beams, post footings, hidden fasteners, and potentially hundreds of screws. Missing even one component means a trip back to the lumber yard and a lost afternoon. Our deck and fence calculators generate a full bill of materials for each project type so you can place a single, complete order before you start building.

Each calculator is designed around the way these projects are actually built. The Deck Board Calculator factors in board length optimization and waste from cuts so you order the right number of boards in the right lengths. The Fence Calculator covers the entire structure — posts at the correct spacing, horizontal rails, pickets with gap allowance, and concrete for every post hole — so nothing gets forgotten. The Post Hole Concrete Calculator handles the geometry of round holes with square posts and returns bag counts in the sizes your store actually sells. And the Concrete Slab Calculator covers footings, pads, and slab-on-grade pours for projects that need a solid foundation. Together, these tools take you from rough measurements to a purchase-ready shopping list in minutes.

All Deck & Fence Calculators

Choose a calculator to plan your deck or fence project.

Deck Board Calculator

How many deck boards and fasteners do I need?

Calculate boards, hidden fasteners, and screws with length optimization and waste factors.

Calculate →

Fence Calculator

How many posts, rails, and pickets for my fence?

Calculate a full fence bill of materials — posts, rails, pickets, concrete, and hardware.

Calculate →

Post Hole Concrete Calculator

How many bags of concrete per post?

Calculate concrete bags for fence posts and deck footings with post displacement math.

Calculate →

Concrete Slab Calculator

How much concrete for a slab or footing?

Calculate cubic yards and bags for slabs, footings, and pads with thickness options.

Calculate →
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Landscaping Calculators → Paver & Hardscape Calculators →

Frequently Asked Questions

How deep should fence and deck posts be set? +
The standard rule is to bury one-third of the total post length underground. For a typical 6-foot privacy fence using 8-foot posts, that means a 2.5- to 3-foot deep hole. Deck posts that support structural loads usually require a minimum depth of 42 inches or below the local frost line, whichever is deeper. Check your local building code before digging — some jurisdictions require inspections for post footings, especially on decks that are attached to the house. Our Post Hole Concrete Calculator asks for post diameter and hole depth so it can return the exact number of bags you need for each hole.
How much concrete do I need per fence post? +
A standard 4x4 fence post set in a 10-inch diameter hole that is 30 inches deep requires roughly 0.4 cubic feet of concrete — about one 50-pound bag of fast-setting mix. A 6x6 deck post in a 12-inch diameter hole that is 42 inches deep uses closer to 0.8 cubic feet, or two 50-pound bags. These numbers vary depending on your exact hole dimensions and how much of the hole the post displaces. Our Post Hole Concrete Calculator does the displacement math for you and returns bag counts for 40-pound, 50-pound, and 80-pound bag sizes so you can match what your local store carries.
Should I run deck boards diagonally or parallel to the house? +
Parallel boards (running perpendicular to the joists and parallel to the longest house wall) are the most common choice because they are easier to install, generate less waste from cuts, and create clean sight lines that make the deck feel larger. Diagonal boards — typically set at 45 degrees — add visual interest and can make a small deck feel more dynamic, but they require more cuts at the edges, produce 10 to 15 percent more waste, and demand closer joist spacing (12 inches on center instead of 16) for adequate support. Our Deck Board Calculator lets you select your layout direction and automatically adjusts the board count and waste factor so your order is accurate either way.