Calculator
Formula used
- Rectangle: Area = Length × Width
- Circle: Area = π × (Diameter ÷ 2)²
- Custom: Use your measured area directly
- Base volume: Volume = Area × Depth
- Adjusted volume: Volume × (1 + Waste%) × (1 + Settling%)
- Conversions: 1 yd³ = 27 ft³ · 1 ft³ = 0.0283168 m³
- Bags: ceil(Adjusted volume ÷ Bag volume)
- Truckloads: Adjusted volume (yd³) ÷ Truck capacity (yd³)
- Weight: Adjusted volume × Density × Wetness multiplier
How to use this calculator
- Pick your unit system so labels match your tape measure.
- Select an area shape and enter its measurements.
- Enter your target depth for mulch or compost layering.
- Add waste and settling allowances to avoid shortages.
- Choose a density to estimate weight for transport planning.
- Set bag size and truck capacity for practical ordering.
- Optional: enter average chunk size to estimate piece count.
Example data table
| Use case | Area | Depth | Adjusted volume | Typical order note |
|---|---|---|---|---|
| Vegetable bed mulch | 4 ft × 12 ft (48 ft²) | 3 in | ~0.49 yd³ | Round up to 0.5 yd³ for easy pickup. |
| Tree ring | 8 ft diameter circle | 2 in | ~0.31 yd³ | One small bulk delivery often covers two rings. |
| Garden path | 30 ft × 3 ft (90 ft²) | 4 in | ~1.48 yd³ | Consider extra for topping up after rains. |
Depth targets for common garden uses
Many beds use 2–3 in (5–8 cm) of wood chunks for moisture control. Paths often need 3–4 in (8–10 cm) for longer wear, while compost cover layers can be 1–2 in (2–5 cm). A quick check: every 1 inch applied over 100 ft² equals about 8.33 ft³, or 0.31 yd³. Use this ratio to sanity‑check results.
Waste and settling allowances that match real beds
Chunks spill, bridge over roots, and leave thin edges. A waste allowance of 5–10% suits flat beds, while irregular borders or wheelbarrow spreading can justify 10–15%. Settling depends on size and traffic; coarse chunks commonly compress 10–20% early on. If you top up yearly, entering 10% settling keeps first‑season coverage consistent.
Bags versus bulk ordering comparisons
Bag labels vary, so compare by volume. One cubic yard equals 27 ft³. With 2.0 ft³ bags, that is about 14 bags per yard; with 1.5 ft³ bags, it is 18 bags per yard. In metric terms, 1 m³ is 1,000 L; a 56 L bag needs about 18 bags for 1 m³. Conversions help you price‑shop confidently.
Transport and weight planning using density
Coverage is volume, but logistics are weight. Light softwood chunks may be near 18 lb/ft³, while wet, heavy loads can reach 35 lb/ft³. Example: 1.00 yd³ at 22 lb/ft³ weighs about 594 lb (≈270 kg). If wetness is 1.15, that becomes about 683 lb (≈310 kg). Use the weight output to avoid overloading.
Piece count estimates for counted purchases
For counted purchases, average chunk dimensions matter. The estimate uses packing efficiency (typical 0.55–0.70) to account for air gaps. With a 2×2×1.5 in chunk and 0.62 efficiency, one cubic yard can contain roughly 4,800 pieces. Larger or flatter chunks reduce the count, so measure a small sample and enter realistic averages.
FAQs
How do I pick the right depth?
Use 2–3 inches for garden beds, 3–4 inches for paths, and 1–2 inches for light compost cover. Choose the deeper option for coarse chunks or high traffic, then add a settling allowance.
Should I include waste and settling?
Yes. Waste covers spillage and uneven edges, while settling accounts for compression after watering and walking. Many gardeners use 5–10% waste and 10–20% settling for coarse chunks.
What bag size should I enter?
Use the printed volume on the bag. Common sizes are 2.0 ft³ or about 56 L. If your supplier lists liters, switch to metric so the bag count stays consistent.
Does density change the volume result?
No. Density affects only the weight estimate. Volume depends on area, depth, and your allowances. Use density to plan lifting limits, trailer loads, and delivery decisions.
Why is my piece count so large?
Chunks contain lots of air gaps, and small pieces multiply quickly. The calculator applies packing efficiency to avoid unrealistic counts, but a 2-inch chunk can still yield thousands per cubic yard.
Can I use this for circular tree rings?
Yes. Select the circle option and enter the diameter. The calculator converts the ring area to volume using your depth, then adds waste and settling before showing bags, bulk volume, and weight.