Soil Calculator
Estimate how much topsoil, garden soil, potting mix, or compost you need for your garden beds and landscaping projects.
Typical raised bed depth: 6-12 inches. Topdressing: 1-2 inches.
Estimated Cost Range
How to Choose and Calculate Soil for Your Garden
Getting the right amount and type of soil is one of the most important steps in any garden or landscaping project. Too little soil stunts plant roots, while over-ordering wastes money and leaves you with piles of extra material. This calculator helps you estimate exactly what you need based on your bed dimensions and preferred soil type, so you can order with confidence and avoid unnecessary trips to the garden center.
Understanding Soil Types
Each soil type serves a different purpose. Topsoil is the uppermost layer of natural earth and works well for filling large areas, leveling lawns, or as a base layer in raised beds. It typically weighs around 75 pounds per cubic foot and costs between $30 and $50 per cubic yard when purchased in bulk. Garden soil is a blend of topsoil with added organic matter and nutrients, making it ideal for in-ground planting beds and vegetable gardens. It is slightly heavier at roughly 80 pounds per cubic foot. Potting mix is a lightweight, soilless blend designed specifically for containers and raised planters. At only about 40 pounds per cubic foot, it drains well and provides excellent aeration for root systems. Compost is decomposed organic material that enriches existing soil with nutrients and beneficial microorganisms, weighing approximately 45 pounds per cubic foot.
How Deep Should You Fill Raised Beds?
For most vegetable gardens, a minimum depth of 6 inches is recommended, though 12 inches is ideal for root vegetables like carrots and potatoes. Shallow-rooted plants such as lettuce and herbs can grow well in as little as 6 inches of soil. If you are building a raised bed over existing ground, 8 to 12 inches gives roots plenty of room to spread. For beds placed on concrete, decks, or other hard surfaces, aim for at least 12 inches to provide adequate moisture retention and root space. When topdressing an existing lawn or garden, 1 to 2 inches of compost or topsoil is sufficient.
Quick Reference: Soil Volume by Bed Size
A standard 4 ft by 8 ft raised bed filled to 12 inches deep requires approximately 32 cubic feet of soil, which equals about 1.2 cubic yards. If filled to only 6 inches, you need roughly 16 cubic feet or 0.6 cubic yards. A 4 by 4 foot bed at 12 inches deep needs about 16 cubic feet. Always order 5 to 10 percent extra to account for settling over the first few weeks.
Amending Existing Soil
If your native soil is hard clay or very sandy, blending in compost can dramatically improve its structure. A common approach is to mix 2 to 4 inches of compost into the top 6 to 8 inches of existing ground using a garden fork or tiller. This improves drainage in clay soils and increases water retention in sandy soils. For established garden beds, adding 1 to 2 inches of compost on top each year as a mulch layer gradually enriches the soil beneath as worms and rain work it downward. Testing your soil pH and nutrient levels before amending helps you choose the right additions and avoid over-fertilizing.
Bulk vs. Bagged: Which Is Better?
For projects requiring more than about 2 cubic yards, buying in bulk is almost always more economical. Bulk soil is delivered by truck and dumped in your driveway or yard, and it typically costs $30 to $60 per cubic yard depending on the type. Bagged soil is more convenient for small projects and easier to transport, but it costs significantly more per volume. One cubic yard equals roughly 27 one-cubic-foot bags or about 14 two-cubic-foot bags. If your project needs less than half a cubic yard, bags are usually the simpler choice. For anything larger, bulk delivery saves both money and the hassle of hauling dozens of heavy bags from the store.