Decking needed by deck size
| Deck size | Area | Decking to buy |
|---|---|---|
| 8 × 10 ft | 80 ft² | 194 linear ft |
| 10 × 10 ft | 100 ft² | 243 linear ft |
| 10 × 12 ft | 120 ft² | 286 linear ft |
| 12 × 12 ft | 144 ft² | 344 linear ft |
| 12 × 16 ft | 192 ft² | 463 linear ft |
| 14 × 16 ft | 224 ft² | 539 linear ft |
| 16 × 16 ft | 256 ft² | 616 linear ft |
| 16 × 20 ft | 320 ft² | 757 linear ft |
| 20 × 20 ft | 400 ft² | 947 linear ft |
| 20 × 24 ft | 480 ft² | 1,144 linear ft |
Linear-foot quantities depend on board direction, actual board width, installed gap and waste. Verify decking installation requirements with the product manufacturer.
Deck board formula
Rows = deck width in inches ÷ (actual board width + installed gap), rounded up. Then multiply rows by the board run length and apply your waste factor. Convert linear feet to stock boards only after choosing the board lengths and cut layout.
Example: 12 × 16 deck
With boards running 12 feet and rows spanning the 16-foot dimension, 5.5-inch decking with a 1/8-inch gap requires about 463 linear feet including 10% extra.
Board width, spacing and stock length matter
A nominal board name does not necessarily equal its actual face width. Measure or use the manufacturer’s actual dimension. Likewise, the correct installed gap can vary by material and product. Once you know the required linear footage, your stock lengths—such as 8, 12, 16 or 20 ft—determine the number of physical boards and where butt joints occur.
Decking is only one part of the takeoff
The Deck Materials Calculator combines decking with framing and foundation quantities. For joist layout, see the Deck Joist Spacing & Count Guide, and use the Deck Planning Hub to continue the project.
Frequently asked questions
How many deck boards do I need?
Divide the deck width by the installed board width plus gap to estimate the number of rows, multiply the rows by the board run length, then add waste. Board direction and available stock lengths affect the final number of boards to buy.
How much space should I leave between deck boards?
The installed gap depends on the decking material, moisture condition and manufacturer guidance. This reference chart uses a 1/8-inch planning gap only; use the spacing specified for the product you install.
How do I convert linear feet of decking to boards?
Divide required linear feet by the stock board length and round up, then account for the actual cut layout. A mixed-length layout can reduce waste compared with assuming every row uses one stock length.