It assumes a single-level rectangular deck with joists running along the long side. Adjust the board length and width to match what is in stock locally - longer boards reduce waste. The cost rollup is the last step: enter prices per piece and the tool returns a budget figure.
Calculator
Formula used
Joists = ⌈length ÷ spacing⌉ + 1 · Boards = ⌈width ÷ (board width + gap)⌉ × rows
How to use the Deck Material Estimator
- Enter the deck length and width in feet.
- Pick the joist spacing (16 in is standard for composite and hardwood).
- Set the board width and length to match what is in stock locally.
- Add the post spacing and per-piece prices for a cost rollup.
About this tool
The Deck Material Estimator is built for speed and accuracy: every calculation runs in your browser, so your data never leaves your device and the result updates as you type. It works equally well on a phone, a tablet or a desktop, and it is free to use as many times as you like.
Common use cases
- Planning a backyard deck before calling the lumber yard.
- Comparing board-on-board vs picture-frame layouts.
- Ordering joist hangers and concrete bags.
- Sizing a deck to fit a specific lumber length.
Tips for the best result
- Use the latest figures you have - even a small change in rate or term can shift the outcome by hundreds.
- For annual figures, divide by 12 to get a monthly number you can compare with the result.
- Bookmark this page and revisit the calculation as the inputs change.
Frequently asked questions
What is the standard joist spacing?
16 inches on centre is the most common choice for composite and hardwood decking. 12 in is used for premium or thinner boards, 24 in only for very rigid materials.
Do I need a permit?
Most municipalities require a permit for any deck over 30 inches high or larger than 100 sq ft. Always check before pouring footings.
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