Soil Volume Calculator — Raised Bed & Topsoil Estimator
Calculate how much topsoil, garden soil, or raised bed mix you need in cubic yards, cubic feet, and bags. Works for raised beds, garden plots, and lawn top-dressing.
How to Use This Calculator
- Select the shape of your raised bed or garden area
- Enter the dimensions for your shape
- Choose the soil depth (12 inches is ideal for most vegetables)
- Select the soil type you plan to use
- Click "Calculate Soil Volume" for cubic yards, cubic feet, and bag counts
How the Calculation Works
volume_ft³ = length_ft × width_ft × depth_ft
cubic_yards = volume_ft³ / 27
bags_1cuft = ceil(volume_ft³ × settling_factor)
bags_0.75cuft = ceil(volume_ft³ × settling_factor / 0.75)
// For rectangular, circular, or L-shaped beds
circle_volume = π × radius² × depth_ft
l_shape_volume = (length1 × width1 + length2 × width2) × depth_ft Soil volume is the product of length, width, and depth all in the same unit (feet). Cubic feet divided by 27 gives cubic yards, the standard unit for bulk orders. A 15% settling factor is applied since loose soil compresses after watering and foot traffic. Bag counts use standard 1 cu ft and 0.75 cu ft (40 lb) bag sizes common at home improvement stores.
Variables:
- volume_ft³: Total volume of soil needed in cubic feet
- cubic_yards: Volume in cubic yards for bulk delivery orders
- settling_factor: Multiplier (1.15) to account for 15% soil settling
- bags_1cuft: Number of 1 cu ft (40–50 lb) bags needed
- bags_0.75cuft: Number of 0.75 cu ft (40 lb) bags needed
Pro Tips
- Fill raised beds with a mix: 60% topsoil, 30% compost, 10% perlite for excellent drainage and fertility
- Soil settles 15–20% over time — order 15% extra, especially for new raised beds
- Standard topsoil bags are 0.75 cu ft or 1 cu ft — bulk delivery is cheaper for orders over 1 cubic yard
- For raised beds deeper than 12", consider filling the bottom 6" with wood chips or logs (Hugelkultur) to save on soil cost
- Test your soil pH before planting — most vegetables prefer pH 6.0–7.0
Recommended Products
Frequently Asked Questions
How much soil do I need for a 4x8 raised bed?
A standard 4×8 raised bed that is 6 inches deep needs: 4 × 8 × 0.5 = 16 cubic feet = 0.59 cubic yards. At 12 inches deep: 4 × 8 × 1 = 32 cubic feet = 1.19 cubic yards. Add 15% for settling — approximately 1.4 cubic yards for a 12-inch deep 4×8 bed.
How many bags of soil do I need for a raised bed?
For a 4×8 bed at 6" deep (16 cu ft + 15% settling = 18.4 cu ft): approximately 19 bags of 1 cu ft soil, or 25 bags of 0.75 cu ft (40 lb) soil. Buying by the bag is 2–4× more expensive than bulk delivery for orders over 1 yard.
What is the best soil mix for raised bed vegetable gardens?
Mel's Mix (popularized by Square Foot Gardening) is 1/3 compost, 1/3 peat moss or coconut coir, 1/3 coarse perlite or vermiculite. A simpler mix is 60% topsoil or garden soil + 30% compost + 10% perlite. Avoid using straight topsoil in raised beds — it compacts easily.
How much does a yard of topsoil weigh?
A cubic yard of topsoil weighs approximately 1,000–1,500 lbs (0.5–0.75 tons) depending on moisture content and composition. Screened topsoil is typically on the lower end; heavy clay soil can exceed 1,800 lbs per yard. Check weight limits before ordering truck delivery.
How deep should raised bed soil be?
Minimum 6 inches for most vegetables and annuals. 12 inches is ideal for most vegetable gardens and allows root crops like carrots. 18–24 inches is best for deep-rooted crops like tomatoes and winter squash, or if the native soil below is poor or compacted.