Rain Garden Soil Calculator – Estimate Soil Volume Easily
A rain garden is more than just a beautiful landscape feature it’s a smart, eco-friendly way to manage stormwater runoff, improve soil quality, and support pollinator-friendly plants. But building one correctly requires careful planning especially when it comes to calculating how much soil, compost, and mulch you’ll need.
Why Soil Volume Matters in a Rain Garden
A rain garden is typically designed in a shallow basin, allowing rainwater to collect and slowly infiltrate into the ground. For it to function properly, the garden must have the correct depth, slope, and soil composition.
To avoid underfilling or over-ordering materials, it’s important to accurately calculate the volume of soil and amendments required.
Use the Topsoil Calculator to Plan Your Rain Garden
Our Topsoil Calculator makes it easy to estimate the exact amount of soil you’ll need based on the garden’s size and depth.
Just enter:
- Length of the garden
- Width across
- Planned depth (typically 6 to 12 inches for rain gardens)
The tool instantly gives you the volume in cubic yards, making it easier to order the right quantity of topsoil, rain garden soil mix, or compost.
What to Fill a Rain Garden With?
A typical rain garden soil mix includes:
- 50–60% sand for drainage
- 20–30% topsoil (loam or sandy loam)
- 10–20% compost for organic content
Use the calculator to determine how much of each you’ll need based on the total soil volume.
Why the Calculator Helps
- Prevents waste from over-ordering materials
- Ensures proper water infiltration by helping you meet the correct depth
- Saves time during garden setup
- Works with irregular shapes by adjusting the area dimensions
- Great for residential, commercial, or community rain gardens
Final Word
Creating a functional and beautiful rain garden starts with proper soil planning. Use our Topsoil Calculator to determine exactly how much soil and compost you’ll need and build a garden that handles water wisely and supports native plants naturally.
Frequently Asked Questions (FAQs)
1. What is a rain garden used for?
A rain garden captures and absorbs rainwater runoff, helping reduce flooding and filter pollutants before they reach storm drains.
2. How deep should a rain garden be?
Most rain gardens are 6 to 12 inches deep, depending on soil type and drainage needs. Deeper beds are used for higher runoff zones.
3. How do I calculate soil for a rain garden?
Use the Topsoil Calculator by entering your rain garden’s length, width, and depth. It shows soil volume in cubic yards.
4. What type of soil should I use in a rain garden?
A mix of sand, topsoil, and compost is best. The soil should drain well while supporting native and deep-rooted plants.
5. Can I use bulk bags for rain garden soil?
Yes. Once you know the required volume from the calculator, you can order bulk bags of custom soil blends or compost accordingly.