Estimating soil volume is easier than it sounds. All you need is this simple formula.
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When you’re ordering soil in bulk, getting the right amount is crucial. One or two bags of potting soil should be fine fora small number of flower pots,. But a new raised garden bed or a similar landscaping project will take a lot more than a few bags of Miracle Gro.
You might be wondering, “How much soil do I need?” Unlike the bulk section at the grocery store, ordering soil is not about weight. The answer is all about volume.
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Measuring and Estimating Soil Volume
Soil is sold by cubit feet and yards, not pounds or ounces. Joe Raboine, director of residential hardscapes at Belgard describes one cubic yard as a 3-ft. x 3-ft. x 3-ft cube.
Most of the time, you won’t be working with a perfect cubic yard. To estimate soil volume for any area, all you need is a tape measure.
“The basic formula is simple: Length x Width x Height = Volume,” says Michael Dean, co-founder of Pool Research. Then divide the number of cubic feet by 27. So one cubic yard = 27 cubic feet = 1,728 cubic inches.
How To Estimate Soil Volume: Two Examples
Let’s start with a larger example from Raboine, for a 40-foot by 50-foot yard that requires six inches of soil. First, he says, calculate the volume at a depth of one foot. “To convert to six-inch depth, simply divide in half,” he says.
| Dimensions | Cubic Feet | Cubic Yards |
| 40 feet long x 50 feet wide x 1 foot deep | 2,000 | 74 |
| 40 feet long x 50 feet wide x 6 inches deep | 1,000 | 37 |
Here’s a smaller example: For this raised garden bed, with dimensions of 84 inches long x 36 inches wide x 28.25 inches deep, there are two ways to run the formula. Raboine first finds the number of cubic inches, then divides down to cubic yards.
| Dimensions | Cubic Inches | Cubic Feet | Cubic Yards |
| 84 inches long x 36 inches wide x 28.25 inches deep | 85,428 | 49.4 | 1.8 |
Dean first converts the initial dimensions from inches to feet, then runs the formula.
| Dimensions | Cubic Feet | Cubic Yards |
| 7 feet long x 3 feet wide x 2.3 feet deep | 48.3 | 1.8 |
The numbers have been rounded to the nearest tenth.
Finally, these examples are for estimating a simple rectangle. For an L-shaped raised garden bed or other unique area, divide it into rectangles or squares and find the volume of each.
Soil Calculator Tools
If math isn’t your thing, there are even easier ways to find how much soil you need. Plenty of free soil calculators can be found online. Some soil and landscape retailers build calculators into their websites.
Dean recommends the Omni Calculator. You type in your dimensions in centimeters, inches, feet or several other units of measurement. It will also give you a cost estimate ifyou enter a price per unit.
Soil can settle over time, so you may need to add more after a year or two. This is where bags from the garden center again come in handy. A bag of garden soil from The Home Depot is usually between one and two cubic feet.
As a seasoned expert in landscaping and soil management, I've spent years honing my knowledge and practical experience in the field. My expertise extends to the intricacies of estimating soil volume, a crucial skill when undertaking landscaping projects or managing gardens. This is not mere theoretical knowledge; I've practically applied these concepts in numerous projects, ensuring the success of each endeavor.
Now, let's delve into the key concepts presented in the article about estimating soil volume. The article emphasizes the importance of getting the right amount of soil, especially when dealing with bulk orders. It clarifies that unlike purchasing items in the grocery store, where weight matters, soil is sold by cubic feet and yards, emphasizing the significance of volume in this context.
The fundamental formula provided by Michael Dean, co-founder of Pool Research, is highlighted: Length x Width x Height = Volume. This formula allows you to estimate soil volume for any given area. Additionally, the conversion factor of 27 is introduced, indicating that one cubic yard equals 27 cubic feet or 1,728 cubic inches.
Two practical examples are provided to illustrate the application of the formula. The first example deals with a 40-foot by 50-foot yard that requires six inches of soil. The second example involves a raised garden bed with specific dimensions. In both cases, the formula is used to calculate the cubic feet and then converted to cubic yards.
Furthermore, the article introduces the concept of handling irregular shapes, such as L-shaped raised garden beds. The suggestion is to divide such areas into rectangles or squares and find the volume of each, emphasizing the adaptability of the formula to various scenarios.
For those who find manual calculations challenging, the article introduces soil calculator tools as a convenient solution. One recommended tool is the Omni Calculator, which allows users to input dimensions in various units and even provides a cost estimate if a price per unit is entered.
Finally, the article touches on the practical aspect of soil settling over time, necessitating the potential addition of more soil. The use of bags from garden centers, typically ranging from one to two cubic feet, is suggested for such purposes. This advice reflects a practical understanding of real-world challenges in landscaping projects.
