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Free Deck Material Calculator
Estimate deck boards, joists and screws for a rectangular deck.
Rows of boards come from the deck width divided by board width plus gap, and boards to buy are rows times length plus waste, divided by the stock length. Joists are length divided by spacing plus one, and screws are two per board crossing, with waste.
How to use the Deck Material Calculator
- Enter the measurements of the area you are working on.
- Read the amount of material needed, including a waste allowance where relevant.
- Round up when you buy, and check the figures with your supplier.
About the Deck Material Calculator
Estimate deck boards, joists and screws for a rectangular deck.
Home and building jobs are easier to price when you know how much material you really need. A quick estimate also helps you avoid buying too little or too much.
Getting started with the Deck Material Calculator
Using the deck material calculator takes a minute or two. Your entries are saved in this browser, so you can come back later and carry on.
Tips for better results
Posts, footings, beams, ledger and railings are not included. Decks carry people, so span, footing and railing rules in local building codes apply, and a licensed professional should check the structure.
Add 5 to 10 percent for waste, cuts and mistakes.
Measure twice, order once, and check quantities with your supplier.
Privacy and where your data goes
Everything you type into the deck material calculator stays on your own device. Zapxa does not receive your numbers or documents. If you clear your browser data, your saved entries will be removed, so download a PDF of anything you want to keep.
Frequently asked questions
How many joists does a deck need?
Divide the deck length by the joist spacing and add one. A 12 ft deck with 16 in spacing needs 10 joists.
Why leave a gap between boards?
The gap allows drainage and board movement, and the calculator adds it to the board width when working out rows.
Is the deck material calculator free?
Yes. It is free to use with no signup, no watermark and no usage limits.
Is my data private?
Yes. Your inputs are processed in your browser and saved only in its local storage. They are not uploaded to our servers.
Does it work on mobile?
Yes. Zapxa works on phones, tablets and desktops. Use the print button or download a PDF to keep a copy.
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