Compost Calculator – Volume, Weight, Bags & Coverage
Enter your area, pick an application preset (like lawn topdressing or garden bed), and set a depth. The calculator shows compost volume in metric and imperial units, estimated weight, bag counts, coverage per bag, and convenient wheelbarrow and truckload equivalents. Presets keep it simple while you can still edit depth to match your project.
How to Use
- Choose Unit System and Area Shape (or enter a direct area).
- Select an Application to auto-fill a sensible depth, then adjust if needed.
- Pick a Bag Size and set Waste and Density if you want weight estimates.
- Click Calculate to get volume, bag counts, coverage, loads, and weight.
Coverage Examples (quick reference)
- 1.5 ft³ bag covers ~18 ft² @ 1" · 9 ft² @ 2" · 6 ft² @ 3"
- 2.0 ft³ bag covers ~24 ft² @ 1" · 12 ft² @ 2" · 8 ft² @ 3"
- 3.0 ft³ bag covers ~36 ft² @ 1" · 18 ft² @ 2" · 12 ft² @ 3"
Formulas & Assumptions
- Rectangle area = L × W; Circle area = π × (D/2)².
- Volume = Area × Depth; Waste applied as V × (1 + waste%).
- Weight = m³ × density; conversions: 1 yd³ = 27 ft³; 1 m³ = 35.3147 ft³; 1 ft³ = 28.3168 L.
- Bag coverage (ft²) ≈ (bag ft³ × 12) ÷ depth in inches.
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Important Estimate Disclaimer
The results provided by this calculator are intended as general estimates only and should not be considered precise engineering measurements. Actual material requirements, costs, and quantities can vary significantly based on site conditions, local building codes, soil type, reinforcement requirements, climate exposure, and the intended use of your project.
These calculators are designed to help you plan and budget your project more effectively, but they do not replace professional advice from a qualified contractor, engineer, or building inspector. Always verify your calculations and assumptions with trained professionals before placing material orders or commencing construction.
For more information on the assumptions, formulas, and data used in these tools, see our Data Sources and Methodology pages.
Material estimates, cost figures, and volume calculations are approximate and may not reflect your actual requirements. Always double-check dimensions and project-specific needs, and consider adding a contingency allowance for waste, over-excavation, and unforeseen conditions.
If you are unsure about any aspect of your project — including structural requirements, reinforcement needs, drainage, or load-bearing capacity — consult with a licensed professional before proceeding.