Raised garden beds offer numerous benefits, from better drainage and soil control to easier access and extended growing seasons. However, planning one requires understanding the materials you'll need, primarily soil and lumber. This calculator helps you estimate these quantities accurately.
Why Use a Raised Garden Bed?
Improved Soil Quality: You can fill your bed with custom soil mixes, ensuring optimal nutrients and drainage, especially if your native soil is poor.
Weed Control: A defined border helps keep weeds from encroaching, and the initial fill with fresh soil reduces weed seeds.
Pest Deterrent: The height can deter some ground-dwelling pests.
Easier Gardening: Less bending and kneeling, making gardening more accessible for many.
Extended Growing Season: Soil in raised beds warms up faster in spring, allowing for earlier planting.
Calculating Soil Volume
The most critical component of a raised garden bed is the soil. You need to fill the entire volume of the bed. The volume is calculated by multiplying the length, width, and depth of your bed. Our calculator provides this in cubic feet and then converts it to cubic yards, which is a common unit for bulk soil purchases, and also estimates the number of standard soil bags you'd need.
To convert to cubic yards, divide the cubic feet by 27 (since 1 cubic yard = 3 feet x 3 feet x 3 feet = 27 cubic feet).
Estimating Lumber Needs
For the frame of your raised bed, you'll need lumber. The calculator provides the total linear feet required for the perimeter of one layer of your bed. If your bed is, for example, 1 foot deep and you're using 6-inch tall boards, you'd need two layers of boards, so you'd multiply the linear feet by two.
Remember to account for the height of your chosen lumber (e.g., 2x6s are actually 1.5 inches by 5.5 inches) and how many layers you'll stack to achieve your desired bed depth.
Cost Considerations
The cost of your raised garden bed will largely depend on the price of soil and lumber. Soil can be purchased in bulk by the cubic yard (often more economical for larger beds) or in individual bags (convenient for smaller projects). Our calculator helps you estimate these costs based on your local prices.
Example Calculation:
Let's say you want to build a raised garden bed that is 8 feet long, 4 feet wide, and 1 foot deep. You plan to use soil bags that are 1.5 cubic feet each, and bulk soil costs $40 per cubic yard, while individual bags cost $7 each.
Volume of Soil: 8 ft × 4 ft × 1 ft = 32 cubic feet
Linear Feet of Lumber (one layer): (2 × 8 ft) + (2 × 4 ft) = 16 ft + 8 ft = 24 linear feet
This example demonstrates how the calculator can quickly provide these essential figures, helping you budget and plan your gardening project effectively.