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Deck Joist Spacing Calculator

Get a recommended on-center spacing (12″ / 16″ / 24″) by joist size, clear span, and decking type. Planning only — verify with code/manufacturer.

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Deck Joist Spacing Chart (typical planning ranges)

Joist Size24″ o.c.16″ o.c.12″ o.c.
2×6≈ 8.0′≈ 9.5′≈ 10.5′
2×8≈ 10.0′≈ 12.0′≈ 13.5′
2×10≈ 12.5′≈ 15.0′≈ 16.5′
2×12≈ 15.0′≈ 18.0′≈ 19.5′

Composite decking: many brands specify ≤16″ o.c., and ≤12″ when boards are installed at an angle. Always check the manufacturer’s installation guide.