What this calculator does

A starting estimate for the joists, deck boards and screws of a simple rectangular deck.

How to use it

1. Measure the deck length and width.
2. Choose the joist spacing. 16 in is common, and 12 in is stiffer for some composite boards.
3. Add beams, posts, footings and railings separately, because they depend on the height and design.

Why it matters

A deck is a structure that carries people. Spacing, footings and fasteners decide how safe and long lasting it is. Many decks, especially those over a certain height or attached to a house, need a permit in Ontario, so check with your city first.

Tips from the job site

• Footings must go below the frost line.
• Use fasteners rated for pressure treated wood.
• Leave a small gap between boards for drainage and expansion.

These results are estimates. We measure on site before we quote, and we confirm local rules with your city.