Estimate how many decking boards you need from the deck size, board width and gap.
How this calculator arrives at its answer
Enter your deck’s length and width, plus your board width and gap, and this calculator estimates the number of board rows, the total lineal feet and the deck area.
It assumes full-length boards; add extra for cuts and waste.
Step by step
- Enter the deck length and width in feet.
- Enter the board width and gap in inches.
- Read the rows and lineal feet needed.
The formula
rows = deck width × 12 ÷ (board width + gap)
lineal feet = rows × deck length
Worked example
On the values this calculator opens with, the boards needed is 26. Change any field and every figure updates as you type.
Common questions
How many deck boards do I need?
Divide the deck width by the board width plus gap for the number of rows, then multiply by the length for lineal feet.
What gap should I leave?
About 1/8 inch is common for drainage and expansion, though it varies by material.
Should I add extra?
Yes — allow for cuts, waste and the occasional defective board.