Deck Board Calculator
Updated Formulas shown
Rows of boards = deck width ÷ (board width + gap). A 20 × 14 ft deck needs 30 rows; with 20 ft boards that's 33 boards including 10% waste.
Deck boards
33
20 ft boards incl. waste
- Deck area
- 280 ft²
- Rows of boards
- 30
- Joists (16 in on center)
- 16
- Deck screws (2 per joist crossing)
- 1,008
Quick reference
| Deck | Rows | Boards |
|---|---|---|
| 10 × 10 ft | 22 | 25 |
| 12 × 12 ft | 26 | 29 |
| 16 × 12 ft | 26 | 29 |
| 20 × 12 ft | 26 | 29 |
| 20 × 16 ft | 34 | 38 |
| 24 × 16 ft | 34 | 38 |
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Frequently asked questions
What gap should deck boards have?
About 3/16 in for kiln-dried wood and composite, ⅛ in for wet pressure-treated boards (they shrink).
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Estimates only. Check quantities with your supplier or contractor before ordering.