Decking
Deck Board Calculator
Estimate deck board rows, board count, waste-adjusted boards, and an optional cost using your own board price.
Decking
Calculator inputs
Deck Board Calculator Results
Results update in your browser as you edit inputs.
Enter project dimensions to calculate material quantity.
Assumptions
- Boards run in the deck length direction.
- The calculator rounds board counts up to whole boards.
- It does not design framing, joist spacing, stairs, railings, fasteners, or code details.
- Any cost estimate uses only the unit price you enter. The site does not provide live, current, near-me, or store-specific material prices.
Formula
- Deck area = deck length x deck width.
- Board rows = deck width divided by board width plus board gap.
- Boards per row = deck length divided by board length.
- Boards with waste = estimated boards x (1 + waste factor).
Example calculation
Example: 12 x 16 deck
A 12 ft by 16 ft deck using 5.5 in wide, 16 ft long boards with a 1/8 in gap needs about 26 boards before waste and 29 boards with 10% waste.
Common mistakes
- Using nominal board width instead of actual board width.
- Forgetting a waste factor for cuts, bad boards, and layout changes.
- Assuming this replaces local deck code or structural design.
FAQ
Does this calculator include joists or railing materials?
No. It estimates decking boards only. Framing, railing, stairs, hardware, and code requirements should be planned separately.
What waste factor should I use for deck boards?
A common starting range is 5% to 15%. Use more for diagonal layouts, complex shapes, or lower-grade boards.