Raised Bed Wood Calculator
Calculate lumber needed to build a raised garden bed from dimensions and board thickness.
Returns board count, screw quantity, post count, and material cost.
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:
- Calculate perimeter:
2 × (Length + Width) - Determine boards per layer: perimeter divided by board length, rounded up
- Determine number of layers: desired height divided by board height
- 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
These are rough 2026 figures that vary by wood type, region, and lumber market. Enter your own board, post, and soil prices in the calculator for a cost that matches your supplier.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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