Garden Bed Calculator
Plan the materials needed to build your own DIY raised garden planter beds. Calculate the exact number of standard 2x6, 2x8, 2x10, or 2x12 lumber boards, corner post cuts, and cubic feet of soil required to fill the planter.
Exterior length of the planter box frame
Exterior width (3 to 4 feet allows easy harvesting from both sides without stepping on soil)
Total vertical height of the planter walls
Width of dimensional lumber used for box side walls
Total lumber side boards needed to assemble all frame tiers
How to Use This Calculator
- Enter the length and width of your garden bed.
- Select your desired planter height (12 inches is most popular for vegetable roots).
- Choose your lumber size (2x6 or 2x8 boards).
- Take the linear footage and board counts to the lumber store, and order the matching soil volume.
Formula & Calculation Methodology
The number of board courses (tiers) is calculated by dividing bed height by nominal board width. Multiplying frame perimeter by the tier count gives total linear board feet.
Worked Example
Classic 8 ft × 4 ft raised bed, 12" height using 2x6 boards
Compact 4 ft × 4 ft square bed, 6" single-board height
Frequently Asked Questions
What type of wood is best for building raised garden beds?↓
Naturally rot-resistant woods like cedar, redwood, and cypress are the top choices, lasting 10 to 20 years without chemical treatment. Untreated pine or Douglas fir is more affordable but typically lasts 3 to 6 years.
Is modern pressure-treated wood safe for edible vegetable beds?↓
Since 2004, residential treated lumber no longer contains toxic arsenic (CCA). Modern wood uses copper-based treatments (ACQ, MCQ) that university extensions consider safe for edible gardens, though lining the inside with food-grade plastic or landscape fabric provides an extra barrier.
Why should raised beds not be wider than 4 feet?↓
An adult reach is about 2 feet. A 4-foot wide bed allows you to comfortably reach the center from either side without stepping on and compacting the aerated soil.
What is a limitation when building long beds over 8 feet?↓
Raised beds longer than 8 feet require cross-bracing ties (or intermediate 4x4 posts) midway along the long sides to prevent the outward hydraulic pressure of wet soil from bowing the wooden walls.