Decking, Fencing & Timber calculator
Decking Calculator
Estimate deck-board rows and total board length from deck size, installed board width, gaps and cutting waste.
Estimate deck-board rows and total board length from deck size, installed board width, gaps and cutting waste. This estimate is most useful when the inputs reflect the job as it will actually be built, fitted or coated. Give particular attention to board width, gaps and layout. Use the actual installed board width and intended gap. Picture frames, diagonal boards, breaker boards and complex edges increase offcuts.
What you need to enter
The Decking Calculator uses the following project information to calculate the result.
- Deck length
- Deck width
- Board width
- Gap between boards
- Waste (%)
Calculator result
Deck area and board quantity / linear length
How the Decking Calculator works
For deck board quantity and linear metres or feet for a deck area, the calculator uses uses effective board coverage including gap. The mathematics is only one part of the estimate: getting board width, gaps and layout right usually matters more to the real-world result than extra decimal places. Unit conversion happens before the calculation.
Decking Calculator worked example
Decking Calculator example: a 5.5 m × 4.0 m deck uses 140 mm boards with 5 mm gaps. The effective 145 mm module determines board rows; the tool then converts the layout to total board length and adds the selected cutting allowance. Use the numerical result as the starting point, then verify board width, gaps and layout against the material, layout or equipment actually being used.
Important calculation assumptions
For deck board quantity and linear metres or feet for a deck area, use the actual installed board width and intended gap. Picture frames, diagonal boards, breaker boards and complex edges increase offcuts.
Frequently asked questions
What are the essential inputs for the Decking Calculator?
Measure deck length and width and enter installed board width plus the planned gap. Add waste for direction changes and edge cuts. The Decking Calculator then applies those figures to deck board quantity and linear metres or feet for a deck area.
Why should I prioritise board width, gaps and layout over extra decimal precision in the Decking Calculator?
Use the actual installed board width and intended gap. Picture frames, diagonal boards, breaker boards and complex edges increase offcuts. For the Decking Calculator, that is the main reason to verify board width, gaps and layout.
What should I check before buying from the Decking Calculator result?
For the Decking Calculator, round board requirements to available stock lengths and account for board direction, picture-frame edges and reusable offcuts. Board quantity does not determine joist or structural design. Use that check before committing to an order, layout or equipment choice.