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Estimating decking material means accounting for the board's actual coverage width — including the small gap always left between boards for drainage and expansion — not just the deck's raw square footage.
This calculator finds the total linear feet of decking boards needed for your deck.
How it works
Enter the deck's length and width, your decking board's width, the gap you'll leave between boards, and a waste percentage. The calculator finds each board's effective coverage width (board plus gap), determines how many rows span the deck's width, and multiplies by the deck's length.
- Enter deck length (ft).
- Enter deck width (ft).
- Enter board width (in, actual coverage).
- Enter gap between boards (in).
- Enter waste/cutting allowance (%).
- Click Calculate to see your results.
Examples
16×12 ft deck, 5.5" boards
A 16 ft by 12 ft deck using standard 5.5-inch-wide boards with a 0.25-inch gap and 10% waste needs about 457.6 linear feet of decking across 26 rows.
Who should use it
- Ordering the right amount of decking board material for a new deck.
- Comparing material needs across different board widths.
Industry applications
- Deck building and outdoor construction
- Home improvement and DIY projects
Advantages
- Accounts for the gap between boards, not just their raw width.
- Includes a customizable waste allowance for cuts.
Limitations
- Estimates decking (surface) boards only — doesn't calculate joists, beams, or other substructure materials.
Common mistakes to avoid
- Using the board's nominal size (like "2x6") instead of its actual coverage width, which is usually narrower.
- Forgetting to include the gap between boards, which understates the true number of rows needed.
Best practices
- Check your specific decking product's actual coverage width (not the nominal lumber size) before entering it.
Tips
- Composite decking often comes in fixed lengths (like 12, 16, or 20 ft) — after finding your total linear footage here, plan your board layout to minimize seams and offcuts.