Optimal Amount of Soil for a Raised Garden Bed: Unlocking the Secret to Successful Plant Growth!

How Much Soil for a Raised Garden Bed: A Comprehensive Guide

A raised garden bed offers numerous benefits to gardening enthusiasts, including improved soil drainage, better control over soil quality, and easier maintenance. However, determining the right amount of soil required for your raised garden bed can be a bit tricky. In this comprehensive guide, we will walk you through the necessary steps to calculate how much soil you need.

Step 1: Measure Your Garden Bed

The first step in determining how much soil you’ll need is to measure the dimensions of your raised garden bed accurately. Using a measuring tape or ruler, measure the length, width, and height of your garden bed in inches or feet. Write down these measurements as they will be crucial for subsequent calculations.

Step 2: Calculate Total Volume Required

To calculate the total volume of soil needed for your raised garden bed, multiply its length by its width and then by its height. If you measured in inches during Step 1:

Total Volume (cubic inches) = Length (inches) × Width (inches) × Height (inches)

If you prefer using feet:

Total Volume (cubic feet) = Length (feet) × Width (feet) × Height (feet)

Step 3: Convert Cubic Inches to Cubic Feet

If your total volume is initially calculated in cubic inches but you’d like to work with cubic feet instead – which is often more practical when ordering bulk materials – convert it using this formula:

Total Volume (cubic feet) = Total Volume (cubic inches)/1728 

Step 4: Adjusting for Soil Settling

When you fill your raised garden bed with soil, it will naturally settle over time. To account for soil settling, it’s recommended to add an extra 10-20% to the total volume calculated in Step 3.

Bulk Density and Soil Types

It’s important to consider the type of soil you’ll be using in your garden bed as different soils have varying bulk densities. Bulk density refers to how much a given volume of soil weighs. Here are some common types of soils and their average bulk densities:

  • Sandy Soil: Approximately 80-100 pounds per cubic foot.
  • Silty Soil: Around 90-110 pounds per cubic foot.
  • Loamy Soil: Roughly 100-120 pounds per cubic foot.
  • Clayey Soil: Typically weighs between 110-130 pounds per cubic foot.

To determine the weight of the required soil, multiply its calculated volume (in cubic feet) by its respective average bulk density based on the type of soil you plan to use in your raised garden bed.

Purchasing Bagged or Bulk Soil

The next consideration is whether you wish to purchase bagged or bulk soil for filling your raised garden bed. Bagged soil is commonly sold in standard sizes like one-cubic-foot bags or two-cubic-feet bags, which makes calculations easier as long as you know the number required based on previous calculations. For example, if each bag contains one cubic foot of material and you need four cubic feet total, purchasing four bags should suffice.

In contrast, if choosing bulk soil, suppliers typically provide it by weight. Therefore, knowing the average bulk density of your chosen soil type will be essential in calculating how many pounds or tons you’ll need.


Calculating the amount of soil required for your raised garden bed doesn’t have to be a daunting task. By following these simple steps and considering variables like settling and bulk density, you can confidently determine how much soil you’ll need to successfully start your gardening journey. Remember to adjust for any specific factors unique to your situation, such as plants with extensive root systems requiring more depth.

Now that you know the right amount of soil needed for your raised garden bed, it’s time to start preparing for an abundant harvest and enjoy the fruits (and vegetables!) of your labor!