🌱 Compost Calculator
Convert bed dimensions to cubic yards and bag counts to streamline soil amendment projects.
How to Use This Calculator
Measure project area
Determine the length and width of beds, raised planters, or lawn sections.
Select desired depth
Compost topdressing typically ranges from 1/4" to 2".
Enter bag volume
Most retail compost bags hold 1–2 cubic feet—check the label.
Formula
Volume (cu ft) = Length × Width × Depth ÷ 12
Cubic Yards = Volume ÷ 27
Bags Needed = Volume ÷ Bag Size
Converting depth from inches to feet (divide by 12) ensures an accurate cubic-foot calculation.
Full Description
Compost improves soil structure, water retention, and microbial activity. Applying consistent depths helps avoid nutrient imbalances and ensures even coverage.
For large projects, consider bulk delivery priced per cubic yard; for small beds, bagged compost may be more convenient.
Frequently Asked Questions
How much compost should I add?
For lawns, 1/4" to 1/2" is common. For garden beds, up to 2" may be incorporated annually.
Can I mix topsoil and compost?
Yes. Use 30–50% compost in raised bed mixes for balanced drainage and nutrients.
Should I apply compost every year?
Annual light applications maintain organic matter and soil biology.
Does compost replace fertilizer?
Compost adds nutrients gradually but often needs supplemental fertilizer for heavy-feeding crops.