Deck Calculator
A 12×16 ft pressure-treated deck needs about 26 boards, 13 joists, 8 posts, and 8 footings — $2,800–$4,800 in materials. Enter your dimensions for an exact estimate.
Inputs
Estimate
- Deck area192 sq ft
- Decking boards (rounded up)Includes 5% waste for trimming.28
- Joists (16 in O.C., spanning width)13
- Posts (8 ft spacing)8
- Concrete footings (12 in dia × 36 in deep)Each footing needs ~6 bags of 80lb concrete.6
- Estimated material cost — low$2,880
- Estimated material cost — high$4,800
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Try Remodel AI freeHow to estimate deck materials
A deck has four material categories: decking boards (the visible surface), joists (the framing beneath), posts (vertical supports), and concrete footings (anchoring the posts in the ground). A typical 16×12 ft pressure-treated deck costs $2,800–$4,800 in materials.
Decking boards run perpendicular to joists. A standard 5.5-inch wide board needs about 2.18 linear feet of board for every 1 sq ft of deck area. Add 5% waste for trimming and cutoffs. Joists are spaced 16 inches on-center for most residential decks (12 inches for heavy-traffic or commercial decks).
Posts are typically spaced 8 feet apart and anchored in concrete footings 12 inches in diameter and 36 inches deep (below frost line in cold climates). Each footing needs about 6 bags of 80lb concrete mix.
Formulas used
- Deck area
length × widthTotal square footage of the deck surface. - Decking boards
(length × 12 / board_width) × number_of_rows × 1.05Each row covers the deck length; number of rows = deck_width × 12 / board_width. 5% waste added. - Footings concrete
footing_count × 6 bags (80lb concrete)Standard 12 in × 36 in footing uses roughly 6 bags of 80lb concrete mix.
Frequently asked questions
How much decking do I need for a 12×16 deck?+
A 12×16 ft deck = 192 sq ft. Using 5.5-inch wide boards, you need about 418 linear feet of decking, or roughly 26 boards at 16 ft long. Add 5% waste = order 28 boards. Plus 13 joists, 8 posts, and 8 concrete footings.
How far apart should deck joists be?+
Standard residential decking uses 16 inch on-center joist spacing. For composite decking with hidden fasteners or diagonal board patterns, use 12 inch on-center. Heavy traffic and commercial decks: 12 inch on-center always.
How much does it cost to build a 16×12 deck?+
A 16×12 ft (192 sq ft) deck costs $2,800–$4,800 for pressure-treated lumber materials, $4,800–$6,700 for cedar, or $5,800–$11,500 for composite. Add 50–100% for professional labor.
How many footings does my deck need?+
Most residential decks need a footing at each post location, with posts spaced 8 ft apart. A 16×12 ft deck typically needs 8 footings. Larger or higher decks may need 10–12.
Can I build a deck without concrete footings?+
Most building codes require concrete footings below the frost line for any permanent deck. Surface-mount deck blocks are allowed for some low-height (under 30 inches), free-standing decks but check your local code.