Calculator Inputs
Formula Used
Area: Rectangle = length × width. Circle = π × radius². Triangle = 0.5 × base × height. Trapezoid = ((base A + base B) ÷ 2) × height.
Volume: Volume in cubic feet = area × depth in feet. Cubic yards = cubic feet ÷ 27. Liters = cubic feet × 28.3168.
Dry mass: Dry mass = volume × bulk density. This estimates soil weight before adding water mass.
Wet mass: Wet mass = dry mass × (1 + moisture fraction). Water mass = wet mass − dry mass.
Organic matter: Organic mass = dry mass × organic matter percentage.
Blend volumes: Component volume = total volume × component percentage.
pH amendment estimate: Amendment = (area ÷ 100) × pH change × texture factor. Lime is used when target pH is higher. Sulfur is used when target pH is lower.
How to Use This Calculator
- Choose the bed shape that matches your yard section.
- Enter the correct dimensions and soil depth.
- Fill in bulk density, moisture, and organic matter values.
- Select sandy, loam, or clay texture for pH estimation.
- Enter current and target pH values.
- Set your topsoil, compost, and sand blend percentages.
- Add truck capacity and bag size for delivery planning.
- Submit the form and review the result table above.
- Use the graph for blend comparison.
- Download CSV or PDF for sharing and records.
Example Data Table
| Project | Shape | Area | Depth | Bulk Density | Blend | Current pH | Target pH | Estimated Volume |
|---|---|---|---|---|---|---|---|---|
| Raised bed refresh | Rectangle | 540 sq ft | 6 in | 78 lb/cu ft | 60/25/15 | 5.8 | 6.5 | 10.00 cu yd |
| Circular herb plot | Circle | 314.16 sq ft | 5 in | 74 lb/cu ft | 55/30/15 | 6.7 | 6.2 | 4.85 cu yd |
| Slope patching | Triangle | 120 sq ft | 4 in | 82 lb/cu ft | 70/20/10 | 5.5 | 6.4 | 1.48 cu yd |
| Trapezoid bed rebuild | Trapezoid | 308 sq ft | 8 in | 80 lb/cu ft | 50/30/20 | 6.3 | 6.8 | 7.60 cu yd |
Frequently Asked Questions
1. Why does the calculator ask for bulk density?
Bulk density converts volume into mass. That helps estimate delivery weight, handling load, compaction risk, and the effect of moisture on wet hauling totals.
2. What moisture percentage should I enter?
Use field measurements when available. For planning, many workable landscape soils fall near 8 to 20 percent moisture, but actual values vary by weather and storage conditions.
3. Why are there separate dry and wet masses?
Dry mass shows the mineral and organic material weight. Wet mass adds water weight, which matters for transport, staging, loader limits, and bed settlement after placement.
4. How reliable are the lime and sulfur recommendations?
They are planning estimates based on area, pH difference, and texture. Laboratory soil tests remain the best source for precise amendment rates and long-term correction strategy.
5. Why must the blend percentages total 100?
The calculator splits total soil volume into topsoil, compost, and sand fractions. A full 100 percent mix ensures the component volumes and estimated masses remain internally consistent.
6. Can I use this for bagged soil purchases?
Yes. Enter your bag size in cubic feet. The calculator estimates the bag count needed to reach the target soil volume for the selected bed geometry.
7. What does the graph show?
The Plotly graph compares component blend volumes and estimated masses. It helps you see whether topsoil, compost, or sand dominates the order and hauling weight.
8. Should I round up the final order size?
Usually yes. Small losses occur during spreading, leveling, and compaction. Ordering a little extra often prevents shortages, especially for uneven beds or staged deliveries.