Decks: boards, joists, screws, footings and stain

A deck's shopping list comes from its footprint, the board width and the joist spacing. A 16 x 12 ft deck in 5.5 inch boards needs 29 deck boards, 13 joists at 16 inches on center and about 676 screws, with 10% extra boards for cuts, plus footings and stain.

This page gathers every deck calculator and guide we have, from the boards and framing to footings, railings, stairs and the stain that keeps it all looking good. The deck planner puts them in the order you will need them.

Deck materials by size

Worked out by the deck materials calculator: 5.5 inch boards in 16 ft lengths, joists at 16 inches on center, 10% extra boards. Footings vary with the design; check the span tables your inspector uses.

Deck boards and screws

Boards are counted in rows across the deck, then in lengths along each row. Run your board length to suit the deck so the joints land on joists and you are not left with short scraps. Hidden fasteners and face screws are counted differently, and the guide on screws explains both.

Framing: joists, beams and squaring the layout

Joist spacing sets the board span: 16 inches on center suits most wood and composite boards, and diagonal decking usually needs 12. Lay out the frame and check it is square from the diagonals before you set a single post.

Footings

Most decks sit on concrete piers poured in tube forms below the frost line. The tube calculator works out the bags for each pier from its diameter and depth.

Railings, stairs and stain

Railings are usually required once the deck is 30 inches or more above the ground, and the baluster gap is set by code. Stairs need an even rise and run. Finish with a stain or sealer, worked out from the deck surface plus the rails and steps.

Adding shade

A pergola over the deck is a separate frame on its own footings. The pergola calculator lists posts, beams, rafters and the concrete.

Every calculator for this topic

Guides

• 12x12 Deck Material List: Boards, Joists, Screws, FootingsA 12x12 deck (144 sq ft) takes 22 boards, 10 joists, 520 screws and 6 footings (26 bags of concrete). Full list and charts.
• 16x16 Deck Material List: Boards, Joists, Screws, FootingsA 16x16 deck (256 sq ft) takes 39 boards, 13 joists, 910 screws and 9 footings (39 bags of concrete). Full list and charts.
• 8x8 Deck Material List: Boards, Joists, Screws, FootingsAn 8x8 deck (64 sq ft) takes 10 boards, 7 joists, 252 screws and 4 footings (18 bags of concrete). Full list and charts.
• Common Mistakes When Building a Deck (Boards, Joists, Gaps)Deck mistakes: joist spacing, board gaps and stock length. A 16 × 12 ft deck with 5.5 in boards needs 29 boards and 13 joists at 16 in spacing.
• How Many Deck Screws Do I Need? Chart by Deck SizeAbout 396 screws per 100 ft² of decking with joists at 16 in. A 12 × 16 deck needs 676. Screw counts by deck size, board width and joist spacing.
• How Many Floor Joists Do I Need? Spacing, Rim Joists, SheetsA floor 16 ft long needs 13 joists 16 in on center. Charts of joists at 12, 16, 19.2 and 24 in, stock lengths and the 4 x 8 subfloor sheets.
• How Much Deck Stain Do I Need? Gallons by Deck Size and CoverageA 12 × 16 ft deck needs about 1 gallon of stain for one coat at 200 sq ft per gallon, 2 gallons for two coats. Charts by deck size and coverage, with railings.
• How to Calculate Stairs: Rise, Run, Number of Steps and StringerA 108 inch rise needs 15 risers of 7.20 inches and 14 treads of 10 inches, with a stringer 14.7 ft long. Stair charts and the code limits.
• Wood vs Composite Decking: Which Should You Choose?Compare pressure-treated wood and composite decking: upkeep, framing differences, fasteners and what to order for a 12 x 16 ft deck.
• Deck Baluster Spacing and Count: The 4 Inch Rule and a ChartHow many balusters per rail and how far apart? A chart of the count and exact gap for rails of 3 to 10 feet, with the 4 inch sphere rule and how to space them.
• How to Square a Foundation, Deck or Frame: 3-4-5 and DiagonalsCheck a frame is square with equal diagonals or the 3-4-5 rule. Charts of the diagonal for common sizes, a worked example, and how to fix a layout that is out.
• Pergola Materials List: Posts, Beams, Rafters and SlatsWhat to buy for a 12×10 ft freestanding pergola: 6×6 posts, doubled 2×10 beams, 2×6 rafters, 2×2 slats and footing concrete, with a chart for other sizes.
• Deck Materials List: Boards, Joists and Screws for a 12×16 DeckWhat to buy for a 12×16 ft deck surface: deck boards, joists, screws, footing concrete and stain, with quantities, a size chart and what the plans must decide.
• How Many Deck Boards Do I Need? Decking Formula and ChartA 12 × 12 ft deck takes about 29 deck boards of 12 ft (5.5 in wide, 10% waste), plus 10 joists and 520 screws. The formula and a chart of common deck sizes.

Other guides that use these calculators: How Much Concrete for Steps? Yards and Bags by Step Count · Actual Lumber Sizes: Nominal vs Actual 2x4, 2x6, 1x6 and More · Board Feet Chart: How to Calculate Board Feet of Lumber · How to Add, Subtract and Multiply Feet and Inches (With Fractions) · Wheelchair Ramp Length and Slope: 1:12, Landings and Handrails · Privacy Fence Materials List: Posts, Rails, Pickets and Concrete

Answers for common sizes

Already know the size? These pages give the worked answer for one common size each, with the inputs filled in so you can adjust them.

Project planners

Planning the whole job rather than one material? These step-by-step planners put the calculators above in the order you will need them.

Frequently asked questions

Related topics

Estimates only. Quantities depend on your materials, site and supplier, so check coverage and sizes on the label. Follow local building codes for anything structural. How we calculate.