Soil Calculator – Guide & Formulas
Calculate how much soil you need for garden beds and raised beds. Free online soil calculator for cubic feet, cubic yards, bags, and weight estimates.
Calculate exactly how much soil your garden bed or raised bed needs. Enter dimensions to get volume in cubic feet, cubic yards, bags, and estimated weight for your project.
Key Takeaway
Use the free Soil Calculator to calculate how much soil you need for garden beds and raised beds. free online soil calculator for cubic feet, cubic yards, bags, and weight estimates. Get instant results with step-by-step explanations.
How to Use the Soil Calculator
- Enter the length, width, and depth of your garden bed.
- Select the soil type (topsoil, compost, raised bed mix, or potting soil).
- Choose the bag size you plan to purchase for bag count.
- Review total volume in cubic feet, cubic yards, number of bags, and estimated weight.
The Formula
Variable Definitions
- L × W × D: Length × Width × Depth, all in feet
- 27: Conversion factor: 1 cubic yard = 27 cubic feet
- V: Volume of soil needed in cubic yards or cubic feet
- Bags: Number of bags to purchase (bag sizes: 0.5–3 cu ft)
Calculating Soil for a 4 ft × 8 ft × 12 in Raised Bed
Determine cubic feet, bags, and weight for a standard raised bed.
- Step 1: Convert depth to feet: 12 inches ÷ 12 = 1 foot.
- Step 2: Volume = 4 × 8 × 1 = 32 cubic feet.
- Step 3: Convert to cubic yards: 32 ÷ 27 = 1.19 cubic yards.
- Step 4: Using 2 cu ft bags: 32 ÷ 2 = 16 bags needed.
- Step 5: Weight (topsoil at 78 lb/cu ft): 32 × 78 = 2,496 lbs.
Frequently Asked Questions
How many cubic yards of soil are in a pickup truck load?
A standard full-size pickup truck holds approximately 2–3 cubic yards of soil in the bed. A compact truck holds about 1–2 cubic yards. Bulk soil delivery is more economical for projects requiring more than 10 cubic feet.
What is the difference between topsoil, compost, and potting soil?
Topsoil is mineral soil from the earth, good for filling large areas. Compost is decomposed organic matter that adds nutrients. Potting soil is a sterile, lightweight mix for containers with perlite and peat moss for drainage.
How much does a cubic yard of soil weigh?
Weight varies by soil type: screened topsoil weighs 2,000–2,200 lbs per cubic yard, garden soil 1,800–2,200 lbs, compost 1,000–1,400 lbs, and potting mix 400–900 lbs per cubic yard.
How deep should I fill a raised bed?
Minimum 8 inches for leafy greens and herbs. 12 inches is standard for most vegetables. 18–24 inches for root vegetables (carrots, potatoes) and large plants like tomatoes. Deeper beds provide better drainage and root space.
Should I mix different soil types?
A common mix is 60% topsoil, 30% compost, and 10% perlite or vermiculite. This provides a balance of structure, nutrients, and drainage. For raised beds, use a commercial raised bed mix or the Mel's Mix formula (1/3 each: peat, vermiculite, compost).
How much does soil settle after installation?
Expect 10–20% settling in the first few months as organic matter decomposes and air pockets collapse. Fill beds 1–2 inches above your target level. Add fresh compost annually to maintain depth.
Can I use native soil in raised beds?
Yes, if your native soil is good quality loam. Mix 50% native soil with 50% compost for best results. Avoid heavy clay or sandy soil alone. The advantage of raised beds is you can control the soil composition completely.
How many bags of soil do I need per cubic yard?
Using 1 cu ft bags: 27 bags per cubic yard. Using 2 cu ft bags: 13.5 bags (round to 14). Using 3 cu ft bags: 9 bags per cubic yard. Always buy 10–15% extra for settling and gaps.