Compost Calculator
Calculate how much compost you need for garden beds, soil amendment, and lawn topdressing.
Results
Visualization
How It Works
Compost is decomposed organic matter that enriches soil with nutrients, improves drainage in clay soil, and increases water retention in sandy soil. It is the single best amendment you can add to any garden.
The Formula
Volume (cu ft) = Length x Width x Depth / 12
Cubic Yards = Volume / 27
Tons = Cubic Yards x 0.5
Cubic Yards = Volume / 27
Tons = Cubic Yards x 0.5
Variables
- L — Length of the area in feet
- W — Width of the area in feet
- D — Desired depth in inches
- 0.5 — Approximate weight of compost in tons per cubic yard (compost is much lighter than soil)
Example
A 20 ft x 10 ft garden bed at 3 inches of compost needs 50 cu ft = 1.85 cubic yards = 0.93 tons. At $35/yard that costs about $65.
Tips
- Apply 1-2 inches of compost as lawn topdressing in spring to improve soil without smothering grass.
- For new garden beds, till 3-4 inches of compost into the top 6-8 inches of existing soil.
- Municipal compost is often available free or at low cost from your city or county recycling program.
- Finished compost should smell earthy, not sour. Avoid compost that still has recognizable food scraps or hot spots.
- Compost is about half the weight of topsoil per cubic yard, making it much easier to spread by hand.