Deck Material Calculator
Decking orders fail in two ways: too few boards mid-build, or a pile of unused lumber. Enter your deck footprint, board width and joist spacing — you get square footage, lineal feet of decking, board count with waste, and the joist count, all ready for the lumber yard.
How the estimate is built
Decking boards are sold by length: a 16-ft board covers 16 linear feet. The waste factor (10% default) covers cuts, defects and pattern breaks — diagonal patterns need 15–20%.
Joists run perpendicular to the decking at 16 inches on center for standard 5/4 decking (24 in. o.c. only for perpendicular boards and structurally rated products).
This covers decking and joists only — add posts, beams, footings and hardware per your framing plan, and always check span tables for your joist size and species.
Frequently asked questions
How much waste should I add for decking?
10% for straight layouts, 15–20% for diagonal or picture-frame patterns, and more if boards must be seam-matched.
What joist spacing should I use?
16 inches on center is the safe default for 5/4 wood and most composites. Some composite products allow 24 in. o.c. only perpendicular to joists.
Does this include railing and posts?
No — those depend on height, layout and code. This tool prices the deck surface and framing members you can compute from the footprint.
Related tools
- Geometry and framing practice: US residential deck construction conventions (IRC-based). Verify spans against your local code.
Last updated: 2026-09-08