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Deck Board Calculator

Calculate deck boards, joists, and materials. Plan your deck construction with practical material estimates.

Deck Material Calculator

Deck Length (feet)

Deck Width (feet)

Board Width (inches)

Gap Width (inches)

Board Length Available

Price per Board

Standard deck spacing: 16" on center joists, 1/8" board gaps

Getting Your Deck Materials Right

Real talk: the difference between a deck that lasts 30 years and one that falls apart is planning materials correctly. You need the right number of boards, proper joist spacing (16 inches on center, always), and the right fasteners. A standard 5/4×6 Trex composite board costs about $2.50 per linear foot. Pressure-treated is half that but needs staining every 2-3 years. Factor in your time and composite wins long-term. Don't guess—calculate it.

Deck Boards: Pressure-Treated vs. Composite

Pressure-Treated: Cheap upfront, lasts 20+ years if maintained, needs periodic staining and sealing.
Composite (Trex, TimberTech): Premium price, no staining needed, holds color for 25+ years, worth the investment if you hate maintenance.
Cedar/Redwood: Beautiful but requires sealing and rots eventually. Expect 15-20 years with care.
PVC: Nearly maintenance-free, lasts forever, but costs 3-4x more than PT lumber.

Spacing Rules (These Matter)

Component	Standard Spacing	Why It Matters
Joists	16" on center	Prevents bouncing, meets code
Board gaps	1/8" (credit card width)	Water drains; wood expands without buckling
Ledger attachment	16" bolts on center	Deck doesn't separate from house
Support posts	Max 8 feet	Structural strength in the ground
Railing posts	Max 6 feet	Safety—keeps people from falling through

Screws Matter. Use Them.

3.5-inch stainless or coated deck screws. Two per board per joist minimum (some codes want three). Never nails—they pop. Never galvanized in treated lumber (chemical reaction causes decay). Spend the $20 more on proper fasteners. Your deck will thank you.

Frequently Asked Questions

1/8 inch. Use a credit card. Water needs to drain; wood expands when wet. Skip the gap and you're asking for rot. Composite boards might need different specs—check your brand's requirements.

Screws. Always. Nails pop as wood moves. Codes demand screws now anyway. Do it once, do it right.

16" on center is standard and works fine for most decks. Go 12" if you're heavy-loading it or spanning real distance. 16" costs less and passes code—that's the move for most people.

Through the rim joist and 3+ inches into house framing. This is not optional—botch your ledger and your deck separates from the house. People get hurt. Use 1/2" bolts every 16 inches.

Low pressure only (under 500 PSI). Anything higher splinters the wood and shortens deck life. Once a year before restaining is fine. Let it dry a few days before sealing.