Deck Calculator
Estimate deck boards, joists and screws for any size deck.
How does the deck calculator work?
Board count = (deck length ÷ board length) × (deck width in inches ÷ board actual width). A "5/4×6" board is really 5.5 in wide. Joists at 16 in on-center: (length in inches ÷ 16) + 1.
Which guide explains this in more depth?
- Riser-and-tread math plus 2026 material prices for a full stair build. Read the stair calculator cost breakdown guide for the full worked example.
What do people use the deck calculator for?
Deck for a 12×12 Deck
Estimate boards and fasteners for a 12×12 ft deck.
Deck for a 16×20 Deck
Estimate materials for a 16×20 ft deck.
Deck for a Pool Deck
Estimate materials for a pool surround deck.
Deck for a Second-Story Deck
Estimate materials for a second-story elevated deck.
Deck for a Ground-Level Deck
Estimate materials for a floating ground-level deck.
What else do people ask about this calculator?
How many deck boards for a 16×12 deck?
At 12 ft boards and 5.5 in actual width, about 27 boards plus 10% waste — order 30.
How far apart should deck joists be?
16 in on-center for standard decking; 12 in for composite or for spans over 12 ft.
Which related calculators should I use next?
All calculators