Soil Calculator
Calculate fill soil and earth material needed for grade changes, retaining wall backfill, and general landscaping fill.
Formula & Explanation
The soil calculator determines the volume, quantity, and weight of fill soil needed for grading and backfill applications. **Step 1: Calculate Volume in Cubic Feet** Volume (cu ft) = Area (sq ft) × Depth (inches) ÷ 12 Example: 200 sq ft area × 4 inches deep ÷ 12 = 66.67 cubic feet **Step 2: Convert to Cubic Yards** Volume (cu yd) = Volume (cu ft) ÷ 27 Example: 66.67 cu ft ÷ 27 = 2.47 cubic yards **Step 3: Calculate Number of Bags** Bags Needed = ceiling(Volume (cu ft) ÷ Bag size (cu ft)) Example: 66.67 cu ft ÷ 3 cu ft per bag = 22.2, round up to 23 bags **Step 4: Calculate Weight** Weight (tons) = Volume (cu yd) × Density (lb/cu yd) ÷ 2000 Example: 2.47 cu yd × 1300 lb/cu yd ÷ 2000 = 1.60 tons **Important:** Fill soil density depends on soil type (clay, sand, loam), moisture content, and compaction level. Loose fill is 1200-1400 lb/cy; compacted fill can be higher. Always verify density with your supplier.
Assumptions
- •Fill soil is general-purpose dirt, not enriched topsoil-best for grading and fill applications
- •Density varies significantly: clay ~1400-1500 lb/cy, sand ~1300-1400 lb/cy, loam ~1200-1300 lb/cy
- •Loose fill soil will compact over time, potentially requiring additional material for proper grading
- •For retaining walls, use compacted fill at 3-4 foot lifts to prevent settling
- •Always check local codes for fill material requirements, especially in wetland or slope areas
Example Calculation
A 200 square foot area at 4 inches of fill requires approximately 2.47 cubic yards (23 bags) or 1.60 tons of soil.
Inputs
Results
Soil Density by Type, Compaction & Use Cases
| soil_type | density_lb_per_cuyd | compaction | use_case |
|---|---|---|---|
| Sand (loose) | 1200-1300 | Low (80-85%) | Drainage base, decorative |
| Sandy loam | 1250-1350 | 85-90% | General fill, grading |
| Loam (medium) | 1300-1400 | 90-95% | Landscaping, lawn prep |
| Silt (fine) | 1300-1350 | 90% | Fine grading, topsoil base |
| Clay (dense) | 1400-1500 | 95%+ | Structural backfill, retaining walls |
| Fill dirt (mixed) | 1200-1400 | 85-95% | General purpose grading |
Frequently Asked Questions
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