Deck board calculator
Enter the deck size and the board you are using. Jobmath gives boards and joists.
How it's calculated
Each step, in the order Jobmath runs it.
| Step | Formula |
|---|---|
| Rows of boards | Deck width in inches ÷ (board width + gap), rounded up |
| Boards per row | Deck length ÷ board length, rounded up |
| Boards | Rows × boards per row × (1 + waste %) |
| Joists | Deck length in inches ÷ spacing + 1 |
Board sizes
Nominal sizes are not the real width; enter the actual width above.
| Nominal | Actual width |
|---|---|
| 5/4 × 6 decking | 5.5 in |
| 2 × 6 | 5.5 in |
| 2 × 4 | 3.5 in |
| Composite, standard | 5.5 in (check the brand) |