Estimates for planning and ordering. Every assumption can be changed.
Decking calculator
Enter the deck size and board size to estimate boards, joists and screws.
Notes
Joists run at right angles to the boards, so each one is as long as the deck width. Softwood decking is commonly laid on joists at 400mm centres; composite boards may need closer joists, so follow the maker's guidance and change the spacing above. The frame, posts and bearers depend on your design and are not calculated here.
These are estimates for planning and ordering. Materials, bag sizes and densities vary by product, so always check the figures on the packaging or with your supplier before you order. For structural work, follow the advice of a qualified builder or engineer.