Measure the Finished Deck Area
Measure the finished deck length and width in metres. Use the actual covered surface rather than rough site dimensions.
Deck area = Length × Width
Decking Tool
Decking Calculator
Estimate deck area, decking boards, waste allowance and material cost.
Metric Calculator
How this calculator works
Deck area is calculated from deck length × deck width.
Coverage per board is calculated from usable board width × board length.
The deck area is divided by board coverage to estimate the basic number of boards.
Waste allowance is then added before the final board quantity is rounded up.
DECKING PLANNING GUIDE
Plan Decking Boards, Waste and Cost Before You Order
Use these six practical checks to turn your deck dimensions into a more reliable decking-board estimate before purchasing materials.
Use the Usable Board Width
Enter the usable face width of one decking board. The calculator converts millimetres to metres before working out board coverage.
Board width (m) = Board width (mm) ÷ 1,000
Calculate Coverage Per Board
Each board covers an estimated area based on its usable face width and its full entered length.
Board coverage = Board width × Board length
Estimate Boards Before Waste
Divide total deck area by coverage per board. The basic quantity is rounded up because partial boards still require a complete board to be purchased.
Base boards = Round up (Deck area ÷ Board coverage)
Add a Waste Allowance
Waste helps cover cuts, defects and layout adjustments. More complex deck shapes may need a larger allowance than simple rectangular layouts.
Final boards = Round up (Raw boards × (1 + Waste %))
Estimate Material Cost
Enter an optional price per board to estimate the decking material cost. Confirm current supplier pricing before placing the final order.
Estimated cost = Final boards × Price per board
Before Ordering Your Decking
Confirm board orientation, expansion or drainage gaps, joist spacing, available stock lengths and the cutting layout before purchasing.
The calculator estimates board quantity from surface coverage. It does not replace structural design, manufacturer installation instructions or local building requirements.