How to use this deck material calculator
Planning a deck starts with a measured footprint and the direction you want the deck boards to run. This estimator assumes boards run along the length entered and joists run across the width. It calculates a materials planning allowance, not an approved structural framing design.
Step-by-step instructions
- Measure overall deck length and width in feet.
- Choose the actual visible face width of your decking and the planned gap.
- Adjust joist spacing and board waste, then review the material estimate.
Calculation formula
Important assumptions and limitations
Simple rectangle, straight board courses and two fasteners per board/joist crossing. Stock-board equivalents ignore cut optimisation, staggering, blocking and joins. Beam, ledger, footing and post design are excluded.
For material orders, confirm package yields, stock sizes and installation instructions with the actual manufacturer or supplier. Your building department determines the applicable local code; a quantity estimator is not a structural design or permit approval.
Frequently asked questions
Does this design a code-compliant deck?
No. Structural joist sizes, spans, beams, ledgers, guards and footings require a design based on your specific site and applicable code.
Why include waste?
Cutting, damage and layout changes increase material needs. The default allowance is a starting estimate, not a substitute for a cut list.
We publish formulas and assumptions so you can verify an estimate. Learn about our methodology or report an issue.