Enter the deck, board, gap, pattern, and stock length. Get board quantity, a low-joint cutting plan, joists, face screws, hidden clips, cutting loss, spare boards, and board cost.
Example values shown — enter your project measurements.
See results ↓Use finished deck dimensions. Board length is the direction the decking will run.
Pattern defaults: straight 10%, diagonal 15%, herringbone 15%. Adjust for defects and complex borders.
The framing counts are planning estimates. Confirm spans, blocking, stair framing, beams, posts, railings, and local code with the project plan.
The straight-layout plan prioritizes fewer butt joints. Patterned layouts use total linear-foot yield because exact cut lengths depend on the drawing.
The extra gap in the numerator avoids counting a gap after the last board. Actual border boards may need ripping to width.
For straight decking, the base plan keeps one final cut piece per course and pools identical cuts where several fit on one stock board.
This is a quantity estimate at 16 inches on center, with an outside joist at each end. It does not size the joists or verify their span.
Hidden fasteners count one field clip at each board joint plus start/end clips. Product systems differ, so use the manufacturer’s schedule for ordering.
These starter plans use 5.5-inch boards, a 1/8-inch gap, straight layout, 10% waste, and a stock length chosen to avoid butt joints.
| Deck size | Stock board | Boards to buy | Joists @ 16 in | |
|---|---|---|---|---|
| 10 × 10 ft | 12 ft | 25 | 9 | |
| 12 × 16 ft | 12 ft | 39 | 10 | |
| 20 × 20 ft | 20 ft | 48 | 16 |
Counts exclude picture-frame borders, stairs, fascia, railings, blocking, beams, posts, and structural hardware.
The cheapest board order is not always the lowest lifetime cost. Compare maintenance, heat, appearance, and substructure requirements before choosing.
Familiar to cut and fasten, widely stocked, and easy to replace one board at a time. Expect ongoing cleaning and finishing.
More consistent board quality and no staining cycle, but product-specific clip systems and temperature gaps matter.
Board spacing handles drainage and movement. The manufacturer’s current installation guide overrides any general rule.
Fresh, wet boards often shrink as they dry. Many installers place them close together, then let drying create the working gap. Confirm with the lumber supplier.
A common starting point for dry boards, providing drainage without an oversized opening. Local moisture conditions can change the choice.
Side gaps are usually controlled by the clip system. End-to-end gaps can vary with installation temperature, board length, and product brand.
Match actual width, stock length, color or grade, fastener system, and delivery fees before comparing totals.
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Quantity is only one part of a safe deck. Structural sizing, ledger attachment, footings, guards, and permits need a code-compliant plan.
For dry wood, 1/8 inch is a common starting point. Wet treated lumber may be installed nearly tight because it shrinks as it dries. Composite spacing is product- and temperature-specific, so follow the manufacturer’s side- and end-gap tables.
Angled ends create more unusable cutoffs, and borders or picture frames add short cuts. A 15% allowance is a practical starting point for a simple diagonal field; complicated outlines may need more.
This calculator estimates quantity at 16 inches on center. Some composite boards, diagonal layouts, stairs, or heavy-use applications require 12 inches on center. Check the decking manufacturer and local structural code before framing.
Hidden clips create an uninterrupted board surface and consistent spacing. Face screws are usually simpler to inspect and replace. Color-matched plugs are a third option. Use a system approved for the exact decking product.
Most products can change slightly after installation, and the degree varies by cap, pigment, exposure, and product line. Review the manufacturer’s sample policy and fade warranty rather than assuming every composite board performs the same.
A simple low deck may suit an experienced DIYer with a permit-ready plan. Hire help when the project involves a ledger, significant height, stairs, complex footings, unusual loads, or structural details you cannot confidently inspect.
No. The result covers the main deck field. Add the exact perimeter boards, breaker boards, fascia, stair treads, and blocking from the final drawing.
Often yes—for blocking, stairs, or another course—but only when the piece length, support, grain, and manufacturer rules allow it. The straight-layout plan pools equal end cuts; patterned layouts are shown as a linear-foot estimate.
Estimate the site materials around the deck with the rest of the LarkKit construction calculator set.