Deck Material & Cost Calculator
Estimate decking boards, joists, posts, footings, and costs for your new custom deck or patio.
Deck Dimensions
Materials & Details
Estimated Materials
Decking Boards (16')0
Total Deck Area0 sq ft
Joists (12')0 boards
Posts (4x4 or 6x6)0 posts
Concrete Footings0 holes
Estimate is for materials only and includes 10% waste for decking and joists. Railings and stairs are not included.
How This Calculator Works
Building a deck requires precise material estimation. Buying too little lumber delays your project, while buying too much wastes money. Our tool calculates the core framing and decking based on standard construction practices.
The Framing Rules
- Decking Boards: Calculated based on standard 5.5-inch wide boards (the actual width of a nominal 6-inch board) with a standard gap. We automatically add 10% for waste and off-cuts.
- Joists: Assumed to be spaced 16 inches on center. We add an extra joist to cap the end.
- Posts & Footings: Assumed to be spaced every 6 feet along the beams.
Material Costs (2026 Estimates)
- Pressure Treated Pine: ~$15 per square foot. Highly affordable but requires annual maintenance.
- Cedar / Redwood: ~$25 per square foot. Naturally rot-resistant and beautiful, but more expensive.
- Composite (Trex, etc.): ~$35+ per square foot. High upfront cost, zero maintenance.
Frequently Asked Questions
How do you calculate materials for a deck?
To calculate deck materials, first determine the square footage (Length × Width). Divide the area by the square footage of a single decking board (a 16ft x 5.5in board covers ~7.33 sq ft) and add 10% for waste. Then calculate joists (spaced 16 inches on center) and posts (spaced every 6 to 8 feet).
How far apart should deck joists be?
Standard deck joists should be spaced 16 inches on center. If you are installing decking boards diagonally, the joists should be spaced 12 inches on center to prevent the boards from sagging.
Is composite decking worth the extra cost?
Composite decking costs roughly twice as much upfront as pressure-treated wood. However, because it requires no sanding, staining, or sealing, it pays for itself in maintenance savings over 5-10 years and lasts significantly longer.
How many footings do I need for my deck?
You typically need one concrete footing for every deck post. Posts are usually spaced every 6 feet along the supporting beams, which run parallel to the deck's length.