Deck Material Calculator
Use this free deck material calculator to estimate how many deck boards you need from your deck dimensions, board size and spacing. Calculate deck area, board rows, total board quantity, linear feet, waste allowance and optional decking cost.
Deck dimensions
Deck board size
How to calculate deck materials
Start by measuring the deck length and width. Multiply those dimensions to find the total deck area in square feet.
Next enter the actual width of the deck board and the planned gap between boards. The calculator uses those measurements to estimate how many board rows are needed across the deck.
Enter the board length to calculate how many boards are required along each row. If the selected board is shorter than the deck, more than one board may be required for each row.
Finally, add a waste allowance for trimming, damaged boards, defects and layout adjustments. The final result is rounded up to a whole-board purchase quantity.
For other dimensional lumber in the project, use the Lumber Calculator. If your project includes deck stairs, use the Stair Stringer Calculator.
Example deck material list
Deck: 12 ft × 10 ft
Deck area: 120 sq ft
Board width: 5.5 in
Board length: 12 ft
Board gap: 0.25 in
Waste allowance: 10%
Material planning
Deck material list calculator
This deck material list calculator focuses on the decking boards that cover the walking surface of a wood deck.
It estimates the number of deck boards, total linear feet and optional material cost from the dimensions you enter.
Structural materials such as posts, beams, joists, concrete footings, fasteners, railing and hardware depend on the actual deck design and are not included in the board quantity shown here.
Deck board cost formula
Estimated decking cost =
Use the current board price from your supplier for a useful material estimate.
Wood deck material calculator
For wood decking, use the actual board width rather than only the nominal board name. For example, a nominal 1×6 or 5/4×6 deck board may have an actual face width around 5.5 inches.
Board spacing also changes the number of rows required. Enter the gap you plan to use so the estimate reflects your intended deck layout more closely.
Deck material calculator FAQs
How many deck boards do I need?
Enter the deck length and width, board width, board length and spacing. The calculator estimates board rows, boards per row and the final quantity after waste.
How do I calculate deck material?
Calculate the deck area, determine how many board rows fit across the width, determine how many boards are required in each row, then add a waste allowance.
How much waste should I add for deck boards?
A waste allowance around 5% to 15% is often used for planning, depending on board defects, cuts, layout and project complexity.
Does the calculator include the gap between deck boards?
Yes. Enter your planned board gap and the calculator uses it when estimating how many board rows fit across the deck width.
Can I estimate deck board cost?
Yes. Enter a price per board and the calculator multiplies the final board quantity by that price.
Does this calculate joists and beams?
No. This calculator currently estimates decking boards. Joists, beams, posts, footings, railing and hardware depend on the structural design.
Can I use this for a wood deck?
Yes. Enter the actual board width, board length and spacing for the wood deck boards you plan to use.
Why should I use actual board width?
Nominal lumber sizes can differ from actual finished dimensions. Using the actual face width produces a more useful deck board estimate.
More project calculators
Estimate lumber quantity, waste and material cost.
Calculate stair rise, run, angle and stringer length.
Calculate lumber volume and board-foot cost.
Plan material cuts and reduce waste.