Deck Material Calculator
Calculate a fuller deck materials list — boards, joist count, and fasteners — from your deck's dimensions and board spacing.
ft
ft
in
in
Common gap is about 1/4 inch for drainage and expansion
in
Commonly 16 in for residential decks
Full Materials List
Deck Boards Needed
26
Deck Area
192 sq ft
Total Linear Footage
416 ft
Joists Needed
13
Fasteners / Screws
676
The Fuller Deck Materials List
This is the fuller, shopping-list version of a deck estimate — it starts from the same board-count math as the simpler Deck Board Calculator, then adds the joist count (based on your deck's width divided by your joist spacing, commonly 16 inches on-center) and a rough fastener count for attaching boards to joists. If you only need a board count, the simpler calculator is faster to use.
Joists Needed = ⌊(Deck Length × 12) ÷ Joist Spacing⌋ + 1
Fasteners = Boards × Joists × Screws per Crossing
Example
A 16 ft × 12 ft deck using 5.5-inch-wide boards with a 0.25-inch gap needs about 25 boards, each 16 ft long. With joists spaced 16 inches on-center along the 16 ft length, that's ⌊(16 × 12) ÷ 16⌋ + 1 = 13 joists. At 2 screws per board-joist crossing, that's 25 × 13 × 2 = 650 screws.
Common Use Cases
- Building a complete shopping list for a deck build, not just a board count.
- Estimating joist quantity and spacing before framing a deck.
- Planning fastener/screw quantities to avoid running short mid-installation.
- Budgeting the full materials cost of a deck project.
FAQs
What joist spacing should I use?
16 inches on-center is the most common residential joist spacing, though some decking materials (especially composite boards installed at an angle) require tighter 12-inch spacing — check your decking manufacturer's span rating before finalizing spacing.
How is this different from the simpler Deck Board Calculator?
The Deck Board Calculator gives you just the board count and linear footage. This calculator adds the rest of a real materials list on top of that — joist count based on your spacing, and a rough fastener estimate — so you can shop for framing lumber and hardware in the same pass.
Should I add extra for waste on top of these numbers?
Yes — as with the simpler board calculator, add 10-15% extra boards for cutting waste and staggered joints, and buy a modest surplus of joists and fasteners rather than the exact calculated amount.