🪵 Deck & Lumber Calculator
Calculate lumber, hardware, and materials needed for deck construction.
Quick Formula
Decking Boards
Boards = (Deck Area × Waste Factor) ÷ Board Coverage
Joists
Joists = (Deck Width ÷ Joist Spacing) + 1
Posts
Posts = Perimeter Posts + Interior Posts (if needed)
Common Deck Sizes
Standard Dimensions
| Component | Typical Size | Spacing |
|---|---|---|
| Decking | 5/4 × 6" or 2×6 | — |
| Joists | 2×8 or 2×10 | 16" OC |
| Beams | 2×10 or 2×12 | Per span |
| Posts | 4×4 or 6×6 | 6-8' spacing |
Common Calculations
Example: 12' × 16' Deck
Decking (5/4 × 6", 16" OC joists):
- Area: 12 × 16 = 192 sq ft
- Board coverage: 5.5" wide = 0.458 LF per sq ft
- Boards needed: 192 ÷ 0.458 = 419 LF
- With 10% waste: 419 × 1.10 = 461 linear feet
Joists (2×10, 16" OC):
- Deck width: 12 feet
- Joist spacing: 16" = 1.33 feet
- Joists: (12 ÷ 1.33) + 1 = 10 joists
Beams (2×10):
- Deck length: 16 feet
- Beam spacing: 6-8 feet (typically 2 beams)
- 2 beams, 12 feet each
Posts (4×4):
- Perimeter: (12 + 16) × 2 = 56 feet
- Post spacing: 6 feet
- Posts: 56 ÷ 6 = 10 posts
Hardware Quantities
Per Joist Connection
| Hardware | Quantity |
|---|---|
| Joist hangers | 2 per joist |
| Screws | 10-12 per hanger |
| Deck screws | 2 per board per joist |
Related Resources
- Lumber Dimensions Reference - Nominal vs actual sizes
- Concrete Calculator - Calculate post footings
Check Local Codes
Deck construction codes vary by location. Check local building codes for joist spacing, post requirements, and railing height.