Wood and composite deck material estimator
Deck Material Calculator
Estimate surface boards, framing stock, concrete footing bags, fasteners and material cost for a simple rectangular deck. Change every assumption to match the products and plan you are actually building.
Material assumptions referenced to deck installation guidanceUpdated
Project inputs
Set the deck assumptions
Layout
Deck footprint
Surface
Deck boards
Framing
Joists, rim and support beams
Foundation and fasteners
Footings and hardware
Optional material prices
Deck boards to order29 boards
For a 16 ft x 12 ft deck with 10% board allowance.
5.5 in boards with 0.19 in gaps
13 joists at 16 in on center
1 support beam run
6 assumed footings
Purchase checklist
Deck material breakdown
| Material | Quantity | Unit price | Subtotal |
|---|---|---|---|
| Estimated material total | USD 1,568 | ||
Hangers, connectors, flashing, guardrails, stairs, posts, post bases, delivery, tax, tools, labor and permits are not included.
Transparent math
How the deck estimate is calculated
- 1Find deck area and board rows
16 ft x 12 ft = 192 sq ft; ceil(144 in / 5.69 in module) = 26 rows
- 2Convert board coverage into stock boards
ceil(26 rows x 16 ft x 1.10 / 16 ft) = 29 boards
- 3Estimate joist and perimeter framing stock
ceil(192 in / 16 in) + 1 = 13 joists; rim / ledger estimate = 56 ft
- 4Estimate footing concrete and fasteners
6 circular footings = 14.14 ft³ / 0.60 ft³ per bag = 24 bags
Installation assumptions
What to confirm before ordering
Board coverage
Rows use face width plus the entered gap. Composite boards can require product-specific side and end gaps.
Joist spacing
The selected spacing estimates material only. Board orientation, diagonal layouts, loads and the exact product may require closer spacing.
Footing design
Footing count, diameter and depth come from your approved plan. Soil, frost, uplift and local code are outside this calculator.
Do not design a deck from this estimate
Use this result for a supplier list. Follow local code, permits and the board and connector manufacturers' installation instructions. Ask a qualified professional to verify structural or attachment decisions.
Common planning questions
Deck calculator FAQ
How many deck boards should I buy?
The calculator divides the projection by board face width plus gap, adds the allowance, then rounds to full stock boards. Borders, diagonal layouts and long board joints may need more material.
Does this choose joist spacing?
No. Enter spacing from the approved design and board manufacturer's instructions. It only changes the material estimate.
Does the footing result tell me how deep to dig?
No. It converts your entered footing dimensions into concrete volume and bags. Local frost depth, soil and structural requirements determine footing design.
Why are beams shown as stock boards?
The tool estimates stock-length beam members from entered beam runs. It does not select beam size, member count, span or connections.