Garden Soil Calculator
The Garden Soil Calculator estimates the amount of soil you need for your garden bed or landscaping project. Enter the length, width, and depth of your area to find out how many cubic yards of soil to order. This tool helps you plan your garden project and avoid ordering too much or too little soil.
This calculator is for informational purposes only. Verify results with appropriate professionals for important decisions.
Use this free online Garden Soil Calculator to calculate your soil volume. Simply enter your length, width, and depth to instantly get results in cubic yards and cubic feet. This helps you order the right amount of soil for your garden or landscaping project.
How Soil Volume Is Calculated
Soil volume tells you how much material fills a three-dimensional space. The calculator finds the volume in cubic feet first, then converts it to cubic yards because soil is usually sold by the cubic yard. The formula multiplies length by width by depth to get the total space. Then it divides by 27 to switch from cubic feet to cubic yards.
Soil Volume (yd³) = (Length × Width × (Depth ÷ 12)) ÷ 27
Where:
- Length = garden area length in feet
- Width = garden area width in feet
- Depth = soil depth in inches (divided by 12 to convert to feet)
- 27 = cubic feet in one cubic yard
This formula works well for rectangular or square garden beds. It assumes the depth is the same across the entire area.
What Your Garden Soil Result Means
The result shows how much soil you need to fill your garden bed. Most landscape suppliers sell soil by the cubic yard. One cubic yard equals 27 cubic feet. If your result is 1.5 cubic yards, you would order 1.5 cubic yards of soil from a supplier. For smaller projects, you might buy bagged soil. A typical 40-pound bag holds about 0.75 cubic feet of soil.
Here are some common garden sizes and their soil needs:
| Garden Size | Depth | Soil Needed |
|---|---|---|
| 4 ft × 8 ft raised bed | 6 inches | 0.59 cubic yards |
| 4 ft × 8 ft raised bed | 12 inches | 1.19 cubic yards |
| 10 ft × 10 ft plot | 6 inches | 1.85 cubic yards |
| 20 ft × 20 ft plot | 12 inches | 14.81 cubic yards |
Most gardeners order 5 to 10 percent extra soil to account for settling and uneven ground. This gives you a small buffer if the soil compacts after watering.
Accuracy, Limitations & Common Mistakes of the Garden Soil Calculator
How Accurate Is the Garden Soil Calculator?
The calculator gives a good estimate for rectangular garden beds with even depth. The math is exact for simple shapes. However, real soil volume can vary. Soil settles over time, especially after rain or watering. Loose soil from a delivery truck may take up more space than compacted soil in your garden.
Limitations of the Garden Soil Calculator
This calculator works only for rectangular or square areas. It does not work for circular, triangular, or curved garden beds. It assumes the ground is flat and level. Sloped areas need different calculations. The calculator also does not account for soil type, moisture content, or how much the soil will settle after installation.
Common Mistakes to Avoid
- Measuring in mixed units: Make sure length and width are in feet, and depth is in inches. Mixing units like yards and feet will give wrong results.
- Forgetting to add extra: Order 5 to 10 percent more soil than calculated to account for settling and uneven ground.
- Ignoring existing soil: If you already have some soil in your garden bed, subtract that amount from your total order.
Frequently Asked Questions
Who is this Garden Soil Calculator for?
This calculator is for homeowners, gardeners, and landscapers planning to fill garden beds, raised beds, or planting areas. It helps anyone who needs to know how much soil to buy for a project.
How often should I use this calculator?
Use this calculator each time you start a new garden project or need to refill an existing bed. It is helpful in spring when preparing new planting areas or when building raised beds.
Does this calculator work for circular or curved garden beds?
This calculator is designed for rectangular or square areas. For circular beds, you would need a different formula using the circle area. Break irregular shapes into smaller rectangles and calculate each separately for a rough estimate.
What if my garden bed has sloped ground?
The calculator assumes a flat, level surface. For sloped areas, measure the average depth across the bed. You may need more soil on the lower end to create a level surface. Consider consulting a landscaper for complex slopes.
Is the Garden Soil Calculator free to use?
Yes, this calculator is completely free to use with no sign-up required. It works on any device with a web browser.
References
- United States Department of Agriculture, Natural Resources Conservation Service - Soil Health
- University of Minnesota Extension - Soil Management for Gardens
- PennState Extension - Calculating Soil Volume for Raised Beds
Calculation logic verified using publicly available standards.
View our Accuracy & Reliability Framework →