Calculators
Deck Material Calculator
Calculate deck boards, linear feet, joists and screws for a rectangular deck from size, board width, gap and joist spacing.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Ordering materials for a new deck
- Comparing wood and composite costs
- Pricing deck builds
- Planning a DIY project
About this tool
What the Deck Material Calculator does
Deck boards run across the joists, so the number of rows depends on the deck width, the board width and the gap between boards, and the boards per row depend on the deck length and board length. Joists are set at a fixed spacing, commonly 16 inches on centre.
Formula
- Rows = deck width ÷ (board width + gap)
- Boards = rows × ceil(length ÷ board length) × (1 + waste)
- Joists = length ÷ spacing + 1
- Screws = rows × joists × 2
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Deck length (along the boards) | 16 ft |
| Deck width | 12 ft |
| Board width | 5.5 in |
| Gap between boards | 0.13 in |
| Board length | 16 ft |
| Joist spacing | 16 in |
| Waste allowance | 10% |
| Price per board (optional) | $28.00 |
| Result | Value |
|---|---|
| Deck boards | 29 |
| Joists | 13 |
| Linear feet of decking | 416 |
| Deck screws (2 per joist crossing) | 676 |
| Rows of boards | 26 |
| Decking board cost | $812 |
How to read the result
Composite boards usually require 16 inch joist spacing or closer, and 12 inches for diagonal layouts. Check the manufacturer’s span tables.
Stagger board joints over joists and plan board lengths to minimise offcuts.
Quantities are estimates. Check product data sheets and local codes, and confirm with your supplier before ordering.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Divide the deck width by board width plus gap to get rows, then multiply by boards needed per row.
16 inches on centre is common; some decking needs 12 inches.
Two screws at each joist the board crosses.
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Let’s build something worth finding.
Tell us where you want the business to be in twelve months. We will come back with a costed plan, a realistic timeline, and the numbers we expect to move — no obligation, no jargon.
- 30-minute call, no pitch deck
- Fixed-price proposal in 48 hours
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- Response time
- Within 1 business hour
- Where we work
- UK, USA & the Gulf
- Contracts
- No lock-in, monthly rolling
- Working since
- 2023