Raised Bed Wood Calculator

Raised Bed Lumber calculation determines how many boards you need based on your desired bed dimensions and board size.

Standard raised bed dimensions:

• Width: 3-4 feet (0.9-1.2 m) — allows you to reach the center from either side
• Length: typically 4, 6, 8, or 12 feet (1.2, 1.8, 2.4, or 3.7 m) — matches standard lumber lengths
• Height: 6-24 inches (15-61 cm) — deeper beds allow more root growth

Common lumber choices:

• 2×6 boards: 5.5 inches (14 cm) actual height. Stack 2 for 11 inches, 3 for 16.5 inches.
• 2×8 boards: 7.25 inches (18.4 cm) actual height. Stack 2 for 14.5 inches.
• 2×10 boards: 9.25 inches (23.5 cm) actual height. Stack 2 for 18.5 inches.
• 2×12 boards: 11.25 inches (28.6 cm) actual height. Stack 2 for 22.5 inches.

Wood type recommendations:

• Cedar: naturally rot-resistant, lasts 10-15 years. Most popular for garden beds. More expensive.
• Redwood: naturally rot-resistant, lasts 10-20 years. Beautiful but expensive.
• Douglas Fir (untreated): affordable, lasts 3-5 years without treatment.
• Pressure-treated: lasts 15-20 years. Modern treated lumber (ACQ/CA-B) is considered safe for vegetable gardens.

The formula:

1. Calculate perimeter: 2 × (Length + Width)
2. Determine boards per layer: perimeter divided by board length, rounded up
3. Determine number of layers: desired height divided by board height
4. Total boards = boards per layer × number of layers

Additional materials needed:

• Corner posts: 4×4 posts, one at each corner, cut to bed height
• Screws: 3-inch exterior screws, approximately 2 per board end (8-12 per layer)
• Hardware cloth (optional): placed at the bottom to prevent burrowing animals

Cost estimation: Cedar 2×6×8: approximately $8-15 each Cedar 2×12×8: approximately $20-35 each Pine 2×6×8: approximately $4-8 each 4×4×8 cedar post: approximately $10-20 each