How Many Deck Boards for a 12×20 deck?
This calculator is pre-filled to estimate the deck boards for a 12×20 deck. Change any field to match your project, and enter your local price for a precise cost.
Deck Boards calculator
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How to estimate deck boards
- This counts the deck surface only. Joists, beams, posts and fasteners are separate.
- Account for a ~1/8 to 1/4 inch gap between boards for drainage; the 10% waste covers cuts and that spacing.
- Composite and hardwood decking cost far more per board than pressure-treated pine - set your local price above.
Frequently asked questions
How many deck boards do I need?
Divide the deck area by the coverage of one board (width times length), then add ~10% for waste and gaps.