Decking · Free Tool

Deck board & structure calculator.

Real numbers for a residential deck — board count, joists, beams, posts, fasteners, and concrete for footings. IRC-aligned assumptions. Adjust waste and joist spacing for your build.

Inputs

Deck length(ft)

Long side, parallel to boards.

Deck width(ft)

Short side, perpendicular to boards.

Board type

Board length to order

Gap between boards(inches)

1/8″ (0.125) composite · 3/16″ (0.1875) wet PT.

Joist spacing (on center)

Waste factor(%)

Jump to results ↓

Deck area

192

sqft

Deck boards to order

× 16ft

458 linear ft total · 26 rows.

Joists

× deck width

156 linear ft total. 2×8 min for 12″ o.c., 2×10 safer.

Beam material

linear ft

Assumes doubled 2×10 or 2×12. Check your local span tables.

6×6 posts

Below frost line. Check local footing depth requirements.

Concrete bags

× 80 lb

10″ × 48″ sonotube per post. Adjust for frost depth.

Deck screws

700

(1 × 5 lb box)

#10 × 2 1/2″ stainless or coated deck screws.

Field notes. Material counts only. Does not include ledger board hardware, post bases, hurricane ties, flashing, railings, stairs, or finish. Always check your local jurisdiction's span tables and frost depth — this calculator uses common North American residential values but code varies. When in doubt, pull a permit.

For the contractor running this calc

Stop running this math ten times a day.

Our AI Estimator takes a job description and writes the full quote — materials, labor, markup, cover letter, payment terms — in under a minute. Built by a landscaping company that needed it.

See the AI Estimator →Or just email me this PDF →

Want this calculator on your own branded site? We build websites, CRMs, and marketing for contractors who'd rather work than wrangle nine tools. See what Tool Shop builds →

Are you a homeowner who landed here? Have a real contractor build this for you →