Deck Material Calculator
Enter your measurements
Extra to cover cuts, breakage, and mistakes.
Results
- Decking boards39 boards
- Joists13
- Joist material156 linear ft
- Deck screws672
- Deck area192 sq ft
Estimated cost
per sq ft of deck surface (decking material)
Material cost per square foot of deck surface covers pressure-treated decking and framing lumber on the low end (about $3-$6), mid-grade composite in the middle, and premium hardwood or high-end composite near the top (about $11-$13). Installed cost includes footings, framing, decking, a standard rail, and labor; elevated decks, complex layouts, or premium materials push toward the high end.
Estimate only — prices vary by region, supplier, and season. Get a local quote before buying.
The deck material calculator estimates the number of decking boards, joists, and screws you need based on your deck's dimensions, board size, and joist spacing. It adds a configurable waste factor so you order enough material without a second trip to the lumber yard, and it helps you compare a pressure-treated pine deck against pricier composite or hardwood before you commit. Decking boards are commonly sold in 8, 10, 12, 14, and 16-foot lengths. The two widths most homeowners use are 5.5 inches (the actual width of a nominal 6-inch board, such as 5/4x6 or 2x6) and 3.5 inches (a nominal 4-inch board). A nominal 5/4 board is about 1 inch thick once milled. Composite decking comes in similar lengths but is priced by the linear foot or by the board, not by the board foot. A 10 percent waste allowance covers end cuts and boards rejected for crown or defects; diagonal layouts can push waste to 15 percent or more.
How it’s calculated
Decking linear feet = Area ÷ board width, plus waste. Joists = (length ÷ spacing) + 1. Screws ≈ 3.5 per sq ft.
Worked example
For a 16-foot by 12-foot deck (192 sq ft) framed with joists on 16-inch centers and covered with 5.5-inch-wide, 12-foot boards at a 10 percent waste factor, the calculator returns 39 decking boards, 13 joists totaling 156 linear feet of joist material, and 672 deck screws. The screw figure comes from a flat estimate of about 3.5 fasteners per square foot, a quick planning rule rather than a board-by-board count. If you instead tally two screws at every board-joist crossing, the number runs higher, so round up and buy a little extra rather than coming up short mid-job.
Inputs
- Deck length
- 16 ft
- Deck width
- 12 ft
- Board width
- 5.5 in
- Board length
- 12 ft
- Joist spacing
- 16 in
- Waste / overage
- 10 %
Result
- Decking boards
- 39 boards
- Joists
- 13
- Joist material
- 156 linear ft
- Deck screws
- 672
- Deck area
- 192 sq ft
- Estimated material cost
- $576 – $2,496
Materials & pricing near you
Pressure-treated lumber, the most common decking choice, is sold by the linear foot at big-box stores and by the board at independent lumber yards, where you can often hand-pick straighter stock. Prices track the lumber commodity market and tend to run higher in peak building season than in winter. Composite decking is not sold by area-coverage boxes; it ships by the board or linear foot, usually palletized, with price breaks at full-pallet quantities worth asking about on larger jobs. Many distributors set a delivery minimum, so a single yard run can be more practical for a small deck. Most jurisdictions require a building permit for a deck attached to the house or more than 30 inches above grade, and they often require guardrails at that same 30-inch height. Check your local code before framing.
Frequently asked questions
How do I measure my deck area if it's an L-shape or has a cut-out?
Break the deck into rectangles, calculate each section separately, and add the areas together. For a bump-out or an inset around a tree or post, subtract that rectangle from the total. Run each section through the calculator individually so the board and joist counts reflect the actual framing direction in that zone, since boards in adjoining sections often run different ways.
What joist spacing should I use, 12 or 16 inches on center?
For 5/4 pressure-treated decking and most 1-inch-thick composite boards laid straight across the joists, 16-inch on-center spacing is standard and code-compliant. If you run boards on a 45-degree diagonal, drop to 12-inch spacing so the boards span less unsupported distance and feel solid underfoot. Some composite manufacturers also require 12-inch spacing as a warranty condition, so check the product's installation guide before you frame.
How many screws or hidden fasteners do I actually need to buy?
The calculator uses about 3.5 fasteners per square foot as a planning estimate. With visible face screws and the standard two-per-joist pattern, your real count can be higher, so treat the output as a floor and round up. If you use hidden clip fasteners like Camo or the Trex clip system, plan on roughly one clip per board at each joist plus a starter clip at the rim. A 1-pound box of 2.5-inch deck screws typically holds 100 to 150 screws depending on gauge.
Does the calculator account for the rim joist and blocking?
The joist count and linear footage cover the interior joists at your chosen spacing plus the two end joists. It does not include the perimeter rim (band) joist, so add the deck's perimeter length to your joist material order. Mid-span blocking is also not included; code typically calls for a row of blocking on spans over a certain length, so plan roughly one linear foot of blocking per joist bay if your span requires it.