How many deck boards do I need?
Choose board direction, count rows, and turn deck dimensions into linear footage and a starting board count.
Short answer
Measure the deck, choose the direction the boards will run, include the actual board width and gap, then apply an allowance before comparing with a stock board length.
For homeowners making an early deck-board list before a cut and joint layout.
How to do it
Measure the deck
Enter the deck length and width that will receive boards.
Choose board direction
Select whether boards run along the length or the width. This sets the row direction.
Enter board details
Use actual board width, the recommended gap, and the allowance for the material.
Compare stock lengths
Use Advanced settings for a starting whole-board count, then make the final cut layout.
Formula
Rows are counted from the coverage width using board width plus gap. Rows multiplied by board run length gives linear footage before allowance.
Illustrative example
For a 20 × 15 ft deck with boards running along the length, rows are counted across the 15 ft dimension. Add the selected allowance, then compare the result with a stock board length.
Common mistakes
- Choosing direction after the count
- Using nominal width without the gap
- Treating the result as a finished cut list
Before you buy
Check board width, stock lengths, joints, borders, stairs, defects, species, grade, and local availability before buying.
What this guide does not cover
Angles, picture framing, borders, stair treads, joist layout, defects, and the final cut plan can change the order.
Use the calculator
Deck Board Calculator is the primary tool for this guide. You can also browse the other deck & outdoor calculators.