About the Deck Board Calculator
Decking coverage depends on the board's actual (milled) width, not its nominal size - a "2x6" deck board is really about 5.5 inches wide, and using the nominal 6-inch figure would undercount how many boards a deck needs.
How It Works
The calculator divides the deck's total area by the board's actual width (converted to feet) to find total linear feet of decking needed, then divides by the purchasable board length to estimate how many individual boards to buy.
Examples
A mid-size deck
A 16×12 ft deck using 5.5-inch actual-width boards and 12-foot board lengths needs about 461 linear feet, or roughly 39 individual boards including 10% waste.
Wider boards
The same deck area with wider boards needs fewer total boards, since each one covers more surface per linear foot.
Advantages
- Uses actual board width, not the misleading nominal size
- Calculates both total linear feet and individual board count
- Adjustable for any board width and purchasable length
Common Mistakes
- Using nominal board width (like "6 inches" for a 2x6) instead of actual milled width
- Forgetting that framing, joists, and fasteners aren't included in this decking-only estimate
- Not accounting for drainage gaps between boards
Edge Cases to Watch For
- This calculates only the decking boards for the walking surface - framing lumber, joist hangers, and fasteners need to be estimated separately.
- Gaps between boards for drainage (typically 1/8 to 1/4 inch) slightly reduce actual coverage per board compared to an edge-to-edge calculation, which the waste allowance partially absorbs.
- Composite and PVC decking come in different actual widths than wood, so always confirm the specific product's actual width rather than assuming a standard lumber dimension.
Common Use Cases
- Estimating decking boards needed for a new deck build
- Comparing material needs between different board widths
- Budgeting a decking project before ordering