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Deck Calculator
Estimate deck boards, joists and screws for any deck size, board width, gap and joist spacing.
Deck Calculator
Deck boards26 rows across 12 ft, +10% waste
Joists
13 × 12 ft
Deck screws (~350 per 100 ft²)
672
Composite decking often needs 12–16 in joist spacing (check the manufacturer). Ledger, posts and footings need engineering to local code.
Planning estimates only. Building codes, loads and material specs vary — have a licensed engineer or contractor confirm quantities and safety requirements. Disclaimer
Important
Quantity estimates for planning and ordering. Structural members, reinforcement and footings must be designed by a qualified engineer to local code.
Frequently asked questions
Is my data uploaded?
No. The calculation runs entirely in your browser — nothing you type is sent to a server.
Is it free?
Yes — free, unlimited and no sign-up.