Soil Calculator: Free Online Garden Soil Estimator
Use our free soil calculator to determine how much soil, compost, or garden mix you need for raised beds, garden plots, planters, and landscaping projects. Designed for gardeners, landscapers, and homeowners, this tool calculates soil volume from your bed dimensions. Enter your length, width, and depth to get instant results in cubic feet, cubic yards, and bag counts.
How to use this calculator.
- Enter your bed or plot dimensions. Input the length, width, and desired soil depth in feet and inches. For irregular beds, calculate the approximate area first.
- Select your soil type. Choose from garden soil, potting mix, raised bed mix, compost, or topsoil. Each has different density and bag coverage.
- Choose bagged or bulk. Select whether you want results in bags (typically 1–2 cubic feet each) or bulk cubic yards for larger projects.
- Click Calculate. The tool displays total volume and the number of bags or cubic yards needed.
- Adjust for settling. Soil settles 10–20% over the first few weeks after placement. Add 15% extra for filling raised beds.
How do you calculate soil volume for planting and landscaping?
Soil volume is calculated by multiplying the bed area by the desired depth, then converting to the appropriate unit.
Volume (cu ft) = Length (ft) × Width (ft) × Depth (in) ÷ 12
Volume (cu yd) = Volume (cu ft) ÷ 27
Bags Needed = Volume (cu ft) ÷ Bag Size (cu ft)
Where:
- Bag size: Standard soil bags are 1 cubic foot or 1.5 cubic feet. Larger bags of 2 cubic feet are common for garden soil.
- Bulk cubic yard: 1 bulk cubic yard covers approximately 100 square feet at 3 inches deep. It equals 27 bags of 1-cubic-foot soil.
Example calculation.
Let's calculate the soil needed for a raised vegetable bed.
Scenario: A raised bed is 8 ft long, 4 ft wide, and requires 12 inches of soil mix. You're buying 1.5-cubic-foot bags.
- Volume in cubic feet: 8 ft × 4 ft × (12 in ÷ 12) = 32 cu ft
- Convert to cubic yards: 32 ÷ 27 = 1.19 cu yd
- Bags needed (1.5 cu ft each): 32 ÷ 1.5 = 21.33 bags
- Add 15% for settling: 21.33 × 1.15 = 24.53 bags
- Round up: 25 bags
Result: You need approximately 25 bagsof 1.5-cubic-foot soil mix, or about 1.25 cubic yardsif buying in bulk.
Cost comparison: 25 bags at $8 each = $200. Bulk delivery of 1.25 cubic yards at $35/cu yd + $50 delivery = approximately $94. Bulk saves about 50% on this project size.
Tips from the field.
- The 1/3 rule for raised beds. A great soil mix is 1/3 compost, 1/3 peat moss or coconut coir, and 1/3 vermiculite or perlite (Mel's Mix). This provides nutrients, moisture retention, and drainage.
- Bulk delivery minimums are typically 3–5 cubic yards.If your project is smaller than this, bagged soil will likely be cheaper despite the higher per-unit cost.
- Don't fill deep raised beds entirely with soil. For beds deeper than 18 inches, fill the bottom half with logs, branches, or yard waste (hugelkultur method). This saves money and adds slow-release nutrients.
- Amend native soil instead of replacing it. Adding 3–4 inches of compost tilled into the top 6–8 inches of native soil is often more cost-effective and ecologically sound than replacing soil entirely.
- Test your soil before amending. A $15–$30 soil test from your county extension office tells you exactly what nutrients and pH adjustments are needed, saving money on unnecessary amendments.
Disclaimer: This calculator provides estimates for planning purposes only. Actual soil requirements depend on bed construction, settling characteristics, soil composition, and local availability. Soil pricing varies significantly by region, season, and supplier. PavementCalculator.com assumes no liability for material shortages or plant health issues.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
How do I calculate soil for a raised bed?
Multiply length × width × depth (all in feet) to get cubic feet, then divide by 27 for cubic yards. For a 4×8 ft raised bed at 12 inches deep: 4 × 8 × 1 = 32 cu ft (1.19 cu yd). For multiple beds, multiply by the number of beds. A 50/50 blend (50% topsoil, 50% compost) is the standard for vegetable beds. Pre-mixed raised bed soil is available but costs more than mixing your own. Fill beds to the top initially: the soil will settle 1-2 inches over the first month.
How many bags of soil do I need?
Bagged soil comes in: 0.75 cu ft (20-25 lbs), 1.0 cu ft, 1.5 cu ft, and 2.0 cu ft sizes. For a 32 cu ft raised bed: 43 bags of 0.75 cu ft, 32 bags of 1.0 cu ft, or 16 bags of 2.0 cu ft. Bagged soil costs $4-$12 per bag. For projects over 1 cubic yard, bulk delivery is significantly cheaper: $25-$50 per cubic yard vs $150-$400 for equivalent bagged soil. Bulk soil is delivered in minimum loads of 2-5 cubic yards depending on the supplier.
What type of soil should I use for a vegetable garden?
The ideal vegetable garden soil (loam) is: 40% sand (drainage), 40% silt (nutrient retention), and 20% clay (mineral content), with 5-10% organic matter. For raised beds: mix 50% screened topsoil with 50% compost. Add perlite or vermiculite (10-20%) for aeration if the base soil is heavy. For containers: use potting mix (NOT garden soil): it's lighter, drains better, and is sterile (no weed seeds or pathogens). Garden soil in containers compacts and suffocates roots.
How much does a cubic yard of soil weigh?
Dry topsoil: 2,000-2,500 lbs/cu yd (1.0-1.25 tons). Moist topsoil: 2,500-3,000 lbs/cu yd (1.25-1.5 tons). Wet topsoil: 3,000-3,500 lbs/cu yd (1.5-1.75 tons). Potting mix: 800-1,200 lbs/cu yd (0.4-0.6 tons: much lighter). Compost: 1,000-1,500 lbs/cu yd (0.5-0.75 tons). When ordering bulk delivery, know that a standard pickup truck can safely haul about 0.5-1.0 cubic yard. A cubic yard of wet soil can weigh as much as a small car.
How do I improve poor soil?
For clay soil: add 3-4 inches of compost and till to 8 inches deep. Add gypsum to help break up clay. For sandy soil: add 4-6 inches of compost to improve water and nutrient retention. Add organic matter annually: soil improvement is a multi-year process, not a one-time fix. Never add sand to clay soil (creates concrete-like hardpan). Never add clay to sandy soil. The universal soil improver is organic matter (compost, aged manure, leaf mold).
How deep should raised bed soil be?
Most vegetables need 12–18 inches of soil depth. Root crops (carrots, potatoes) need 18–24 inches. Shallow-rooted plants (lettuce, herbs, radishes) can grow in 6–8 inches. Deeper is always better for moisture retention and root development.
How many bags of soil do I need per cubic yard?
One cubic yard equals 27 one-cubic-foot bags, 18 bags of 1.5 cubic feet, or 13.5 bags of 2 cubic feet. Buying in bulk is typically 40–60% cheaper than bags for projects requiring more than 1 cubic yard.
What is the difference between topsoil and garden soil?
Topsoil is the upper 5–10 inches of natural soil and varies widely in quality. Garden soil is topsoil amended with compost and organic matter for planting. Potting mix contains no actual soil and is a soilless blend of peat, perlite, and nutrients for containers.
Can I reuse potting soil from last year?
Yes, but it should be rejuvenated. Old potting soil loses nutrients and structure. Mix 2 parts old soil with 1 part fresh compost and add a slow-release organic fertilizer. Sterilize by solarizing (sealing in black plastic in full sun for 4–6 weeks) to kill pathogens.