Find how many deck boards your deck needs. Each dimension has its own unit selector (in/ft/yd/m).
Decking is estimated by area. Measure each part of the deck (any unit) and add them up. One board covers its length times its actual width - a nominal 6-inch board is really 5.5 inches, so use the preset. Divide the deck area by one board's coverage and add about 10% for waste. Joists, posts and fasteners are separate.