Exterior
Decking Calculator
Estimate decking boards by area and board size. Fast planning tool for backyard decks.
Inputs
Live estimate
Boxes needed
5
- Area
- 100 sq ft
- Area (with waste)
- 100 sq ft
Live estimate
- Mathematical quantity
- 5
- Cut and off-cut allowance
- Informational
- Field conditions
- Not applied
- Adjusted requirement
- 5
- Ordering rule
- Round up to whole board
- Suggested order
- 5
Deck boards are cut to length and around obstructions; short off-cuts become scrap.
What you actually need in the field, before rounding to a supplier-friendly ordering unit.
Estimator confidence
HighDeck boards are cut to length and around obstructions; short off-cuts become scrap.
Why this behavior applies: Deck-board counts already include a waste allowance; the intelligence layer only explains the reason.
- Deck dimensions and board direction — Boards run across the shorter dimension usually waste less material.
- Board length vs deck length — Choosing a stock length that divides evenly into the deck length minimizes end-cuts.
- Spacing between boards — Standard ⅛-in spacing changes the effective width and board count.
- Layout pattern — Picture-frame or diagonal patterns add cut waste; straight lay is most efficient.
- Plan the board layout on paper before ordering — direction affects yield.
- Use hidden fasteners on composites and stainless screws on cedar/redwood.
- Frame joists at 12 inches on center for composites, 16 inches for wood.
- Ordering by area with no waste factor and running short on the last course.
- Framing composites at 16-inch centers and getting sagging boards.
- Skipping picture-frame trim and leaving raw end grain exposed.
Smart tips
- Ordering 5–10% extra is standard on irregular layouts. Running short costs more than the excess.
How it's calculated
Area with waste = area × (1 + waste %).
Boxes = ceil(area with waste ÷ box coverage).
Material assumptions
- Standard board coverage varies by width and length — check your supplier's actual sq ft per bundle.
- Add 10–15% waste for miters, cuts, and pattern layouts.
- Joist spacing: 16 in on-center standard; 12 in for diagonal or 45° layouts.
Frequently asked questions
Related calculators
Structural deck framing (posts, beams, joists) requires engineering and a permit in most jurisdictions.