Topsoil & Soil Calculator
Adjust the parameters below to compute materials and estimate project costs.
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Breakdown Details
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Guidelines & Field Recommendations
• Lawn Seeding: 4 to 6 inches.
• Flower beds: 6 to 8 inches.
• Vegetable Raised Beds: 12 to 18 inches.
Mix Ratio: 70% topsoil to 30% compost is optimal for plant growth.
Calculation Formulas & Steps
Soil Volume (cu yd) = Area × Depth (ft) ÷ 27. If compost ratio is active, volume is split between soil and compost.
Worked Example (Step-by-Step Math)
Multiply area by depth, then divide by 27.
20 ft × 10 ft × (6/12) ft ÷ 27 = 3.70 cu ydCalculate compost fraction.
Compost: 3.70 × 0.20 = 0.74 cu yd; Soil: 2.96 cu ydTopsoil settles heavily when watered.
Soil order: 2.96 × 1.10 = 3.26 cu ydTopsoil Depth Requirements
Optimal soil depths for root systems.
| Project Condition | Reference Metric |
|---|---|
| New Lawns / Turf Seed | 4 to 6 inches depth |
| Vegetable Beds | 12 to 18 inches depth |
Critical Mistakes to Avoid
- !Mistake 1: Buying cheap unscreened fill dirt instead of screened topsoil, introducing weeds and stones.
- !Mistake 2: Not mixing compost thoroughly.
Frequently Asked Questions
What is the ideal topsoil to compost ratio for a vegetable garden?
The ideal soil-to-compost ratio for a raised vegetable bed is 70% topsoil to 30% organic compost. Compost provides essential nitrogen and soil biology, while the mineral topsoil provides structure and holds water.
How much will screened topsoil settle after installation?
Topsoil is highly organic and aerated when delivered. It will settle down by about 10% to 15% after watering, rain, and tamping. If you need a final depth of 6 inches, excavate or build forms to 7 inches and fill it to the top.
How much compost should you mix with topsoil for raised beds?
For raised garden beds, the optimal blend is 70% topsoil to 30% organic compost. This creates a rich, well-draining soil structure that provides slow-release organic nutrients for vegetable and flower roots without compacting.
What is the difference between screened topsoil and unscreened soil?
Screened topsoil is passed through industrial meshes to filter out debris, large stones, roots, weeds, and clay clumps, making it loose and easy to rake. Unscreened topsoil is raw dirt direct from excavations, contains debris, and is only suitable for bulk grading fill.
How many cubic yards of soil do I need for a 10x10 garden?
For a 10x10 foot garden bed (100 sq ft) at a depth of 6 inches, you need approximately 1.85 cubic yards of soil. If using bags of 1 cubic foot, this requires exactly 50 bags of garden soil.
How much volume is in a standard retail bag of soil?
Most garden soil bags are 1 cubic foot. There are 27 bags of 1 cu ft in 1 cubic yard.
What is the difference between topsoil and fill dirt?
Topsoil is the nutrient-dense top layer of ground containing organic matter. Fill dirt is deep subsoil containing rocks and clay, lacking nutrients.
Complete Tools Checklist
- Rake
- Shovel
- Wheelbarrow
- Rototiller (optional)