Deck Board Calculator
Enter your deck dimensions and board size to estimate the number of deck boards, including a waste factor and optional cost.
Results
- Deck boards needed
- 29
- Deck area
- 192 sq ft
- Coverage per board
- 7.5 sq ft
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Enter your deck dimensions and board size to estimate the number of deck boards, including a waste factor and optional cost.
How to use the deck board calculator
- Enter the deck length in ft.
- Enter the deck width in ft.
- Enter the board width in in.
- Enter the board length in ft.
- Enter the gap between boards in in.
- Enter the waste factor in %.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Deck length
- 16 ft
- Deck width
- 12 ft
- Board width
- 5.5 in
- Board length
- 16 ft
- Gap between boards
- 0.125 in
- Waste factor
- 10 %
Results
- Deck boards needed
- 29
- Deck area
- 192 sq ft
- Coverage per board
- 7.5 sq ft
Using the example values above, the deck board calculator returns 29 (deck boards needed). Change any field to match your own project and the numbers update instantly.
How much extra should I order?
Always order a little extra. A 5% waste factor suits simple, square projects; 10% is right for most jobs; bump it to 15–20% for irregular shapes, diagonal patterns, or uneven ground. Running short almost always costs more than the leftover material.
Formula
Boards = deck area ÷ board coverage, × (1 + waste%). Board coverage = (board width + gap) × board length.
Frequently asked questions
- What gap should I leave between deck boards?
- Leave 1/8 in for kiln-dried boards; wet pressure-treated boards can be butted tight since they shrink.
- How much waste should I add?
- Add 10% for straight decks and 15% for diagonal or picture-frame patterns.
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