Deck Calculator
Estimate decking boards, joists, screws, and total linear feet for any deck size — with a waste factor for cuts and instant results.
A nominal 1×6 board is 5.5 in wide.
1/8 in (0.125) is typical for drainage.
16 in on-center is standard.
Add 10% for cuts, and more for diagonal or picture-frame layouts.
How to Calculate Deck Materials
Decking boards run across the joists, so the number you need depends on the deck's dimensions, the actual width of each board, and the gap you leave for drainage. We divide the deck length by the board width plus gap to find how many rows of boards fit, then multiply by the deck depth to get total linear feet. After adding your waste factor, that linear footage is divided by the length of the boards you're buying.
Framing is sized separately: joists are spaced 16 inches on-center by default, so the joist count is the deck length divided by the spacing, plus one. Plan for roughly 2.2 deck screws per square foot — about two screws at every joist crossing. Always round up and keep a few spare boards on hand for mistakes and future repairs.
Frequently Asked Questions
How many deck boards do I need?
Divide your deck length in inches by the board width plus the gap to get the number of rows, multiply by the deck depth for total linear feet, add about 10% for waste, then divide by the length of each board. This calculator does all of that automatically.
How do I calculate decking square footage?
Multiply the deck length by its width. A 16-foot by 12-foot deck is 192 square feet. Add 10–15% extra material to cover the waste from cutting boards to length and from any diagonal or picture-frame patterns.
How many screws per square foot of decking?
Plan for roughly 2.2 deck screws per square foot, which is about two screws at every joist crossing with standard 16-inch on-center spacing. A 200-square-foot deck needs around 440 screws.
Turn Your Measurements Into a Real Floor Plan
Once you know your dimensions, generate a labeled, to-scale floor plan in seconds — then export it to DXF or build it in 3D. No CAD experience needed.
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