Calculate Soil Volume
Select your bed shape, enter dimensions, and instantly see how much soil, mulch, or compost you need in multiple units.
Rectangular Bed Dimensions
Circular Pot Dimensions
Raised Bed Dimensions
Tip: Standard raised beds are 12-24 inches (1-2 ft) tall.
Irregular Area
Tip: For irregular shapes, estimate total square footage or break into smaller rectangles and add them up.
Bags Needed
Cost Estimator
Multiple Beds Calculator
Add multiple beds and areas to calculate combined soil needs.
Soil Mix Calculator
Choose a preset or customize your soil mix ratios. Uses the volume from the calculator above.
Recommended Soil Depths by Plant Type
Use these guidelines to determine how deep your soil should be for different plants.
| Plant Type | Minimum Depth | Ideal Depth | Notes |
|---|---|---|---|
| Lawn / Grass | 4 inches | 6 inches | Top dressing over existing soil |
| Lettuce, Herbs, Radishes | 6 inches | 8 inches | Shallow root crops |
| Annual Flowers | 8 inches | 12 inches | Most bedding plants |
| Beans, Peppers, Squash | 10 inches | 14 inches | Medium root depth |
| Tomatoes, Cucumbers | 12 inches | 18 inches | Deep root systems |
| Root Vegetables (Carrots, Potatoes) | 12 inches | 18 inches | Need loose, deep soil |
| Perennial Flowers | 12 inches | 18 inches | Established root systems |
| Shrubs | 18 inches | 24 inches | Larger root ball |
| Small Trees | 24 inches | 36 inches | Consult species requirements |
How to Calculate Soil Volume
Accurately calculating soil volume saves money and prevents buying too much or too little. The basic formula for rectangular beds is simple: Length x Width x Depth. For circular pots, use the cylinder formula: Pi x (Diameter / 2)squared x Depth. Always measure in consistent units and convert at the end.
Volume Formulas
Rectangle: Length x Width x Depth
Circle: 3.14159 x (Diameter / 2)² x Depth
Irregular: Approximate area x Depth
Divide cubic feet by 27 to get cubic yards.
Bag Sizes Guide
Bagged soil comes in standard sizes: 1 cu ft, 1.5 cu ft, 2 cu ft, and 3 cu ft. For small pots and planters, 1 cu ft bags are convenient. For raised beds, 2-3 cu ft bags reduce trips. For projects over 3 cubic yards, consider bulk delivery.
Soil Types
Topsoil: General-purpose, heavy. Good for filling and grading.
Garden soil: Topsoil with organic amendments. Good for in-ground beds.
Potting mix: Lightweight, sterile. Best for containers.
Compost: Rich organic matter. Mix in for nutrients.
Raised Bed Soil Mixes
The classic raised bed recipe: 60% topsoil for structure, 30% compost for nutrients and moisture retention, and 10% perlite or vermiculite for drainage and aeration. Adjust ratios for clay-heavy or sandy native soils.
How Much Soil Do I Need?
The amount of soil you need depends on your project size and what you are growing. Here are some common scenarios to help you estimate.
Standard 4x8 Raised Bed
Dimensions: 4 ft x 8 ft x 12 in deep
Volume: 32 cu ft (1.19 cu yd)
Bags (2 cu ft): 16 bags
Approx cost: $80-$120
12-Inch Round Pot
Dimensions: 12 in diameter x 10 in deep
Volume: 0.65 cu ft (about 18 liters)
Bags (1 cu ft): 1 bag
Approx cost: $5-$8
Garden Bed Top Dressing
Dimensions: 10 ft x 20 ft x 2 in deep
Volume: 33 cu ft (1.23 cu yd)
Bags (2 cu ft): 17 bags
Approx cost: $85-$130
Mulching a Yard Area
Dimensions: 20 ft x 30 ft x 3 in deep
Volume: 150 cu ft (5.56 cu yd)
Recommendation: Buy bulk at this size
Approx cost: $150-$280 delivered
Frequently Asked Questions
How much soil do I need for a raised bed?
How many bags of soil do I need?
How deep should garden soil be?
What is the best soil mix for raised beds?
How do I calculate soil for a round pot?
How much does soil cost per cubic yard?
Privacy & Limitations
All calculations are performed locally in your browser. No data is sent to any server. This calculator provides estimates based on geometric formulas and standard bag sizes. Actual soil amounts may vary due to settling, compaction, and irregular shapes. Soil settles approximately 10-20% over the first season, so consider buying extra.
Related Tools
- Soil Volume Calculator -- Calculate topsoil and fill dirt for landscaping
- Cubic Yard Calculator -- Calculate cubic yards for landscaping and materials
- Mulch Calculator -- Calculate mulch needed in cubic yards and bags
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This tool FAQ
How much soil do I need for a raised bed?
Calculate the volume by multiplying length × width × depth. A standard 4ft × 8ft × 12in raised bed needs 32 cubic feet (about 1.2 cubic yards) of soil. Use a mix of 60% topsoil, 30% compost, and 10% perlite or vermiculite for best results.
How many bags of soil do I need?
Divide your total cubic feet by the bag size. A 1 cu ft bag covers 1 cubic foot, and a 2 cu ft bag covers 2 cubic feet. For a 4×8 raised bed that is 12 inches deep (32 cu ft), you need 32 one-cubic-foot bags or 16 two-cubic-foot bags.
How deep should garden soil be?
Soil depth depends on what you are growing. Lawns need 4-6 inches, annual flowers need 8-12 inches, vegetables need 12-18 inches, shrubs need 18-24 inches, and trees need 24-36 inches. Raised beds should be at least 12 inches deep for most vegetables.
What is the best soil mix for raised beds?
A common raised bed mix is 60% topsoil, 30% compost, and 10% perlite or vermiculite. For container gardening, use 40% peat moss or coco coir, 30% compost, 20% perlite, and 10% vermiculite. Adjust ratios based on plant needs and drainage requirements.
How do I calculate soil for a round pot?
For a cylindrical pot, use the formula π × radius² × depth. Measure the diameter across the top, divide by 2 to get the radius, then multiply π × radius² × depth. A 12-inch diameter pot that is 10 inches deep needs about 0.65 cubic feet of soil.
How much does soil cost per cubic yard?
Bulk topsoil costs $15-$50 per cubic yard delivered. Bagged garden soil costs $4-$10 per bag (1-2 cu ft). Specialty mixes like raised bed soil cost $30-$80 per cubic yard. Buying in bulk is more economical for projects over 3 cubic yards.