How Many Deck Boards Do I Need?
It depends on your deck’s area, board width, decking angle, and waste. This calculator converts square feet into total linear footage and shows counts for 8′–20′ lengths so you can pick what’s stocked locally.
Your Decking Materials Calculator
Enter your deck size (square feet or exact dimensions), choose board size, joist spacing and decking angle. Results update in real time — no calculate button needed.
1. Total Square Feet
TOTAL SQUARE FEET:
ft²
If you type here, we’ll use this value and ignore the dimensions below.
OR DIMENSIONS
ft
in
ft
in
2. Board Size
We assume actual face widths of 3.5″ (4‑inch boards) or 5.5″ (6‑inch boards) plus a 1/8″ gap.
3. Joist Spacing
4. Decking Angle
5. Total Length Of Perimeter (optional)
ft
Useful if you plan a picture‑frame border. We’ll add this to the total linear footage required.
Your Decking Materials Calculator Results
| BOARD OPTIONS: | REQUIRED: | WASTE: | REQUIRED + WASTE: |
|---|
Board Screws Required: —
Hidden Fasteners Required: —
How the Deck Board Calculator Works
We convert your deck area to the total linear footage of deck boards required, using your selected board face width and a default 1/8″ gap. If you choose 45° decking, we multiply by a diagonal factor (≈1.414) to account for longer runs and offcuts. Finally, we add a standard 5% cut‑waste and show board counts for each common length (8′–20′).
Formulas (simplified)
- Area (ft²) = given ft², or (Length in ft) × (Width in ft).
- Effective coverage width (ft) = (board width in″ + 0.125″) ÷ 12.
- Linear feet required = Area ÷ coverage width × angle factor (1 at 90°, 1.414 at 45°).
- Boards of length L: ceil( linear feet ÷ L ). Waste adds 5% then rounds up.
- Fasteners: boards‑across × joists‑along; screws = intersections × 2, hidden clips = intersections × 1.
Fastener estimates need deck length & width. If only area is provided, we approximate using a square deck with side √area.
Decking Basics & FAQs
What Are Common Deck Board Sizes?
Most projects use 5/4×6 or 2×6 (≈5.5″ face) or 5/4×4 / 2×4 (≈3.5″ face). We include a default 1/8″ gap between boards for drainage and expansion.
What Materials Do I Need for Decking?
Deck boards, joists, posts/footings, fascia or picture‑frame boards, and fasteners. Our fastener count assumes two screws per joist or one hidden clip per joist per board.
How Do I Measure a Deck?
Measure length and width to the nearest inch. For L‑shapes, split into rectangles and add the areas. You can also type the total square footage directly in the first box.