Deck & Joist Estimator
Joists, deck boards and fasteners for a deck
Deck
Boards run across the joists. Screw count assumes two fasteners per board at every joist.
Estimated materials
About Deck & Joist Estimator
The deck and joist estimator counts the frame and surface materials for a deck: how many joists, how many deck boards, and how many screws. Enter the deck length and width, the joist spacing, which direction the joists run, and the board width and gap — the boards are laid across the joists automatically.
The joist count comes from dividing the deck dimension perpendicular to the joists by the spacing (plus the end joist), and the board count divides the deck the other way by the board width plus its gap. Screws are counted at two per board at every joist crossing — the standard fixing pattern — and a wastage percentage covers cuts and culled boards.
Use it to price a new deck or re-boarding job before visiting the lumber yard, free in your browser. It estimates quantities, not structure: joist depth, span limits, beams, and footings come from span tables and your local building code.
How to use Deck & Joist Estimator
- Enter the deck length and width in meters.
- Set the joist spacing in millimeters and choose whether joists run along the length or the width.
- Enter the deck board width and the gap between boards, in millimeters.
- Add a wastage percentage for cuts.
- Read the joist count and length, board count and length, and the number of deck screws.