Compost Calculator
How much compost do you need? Enter your bed size to get cubic yards, bags, and an estimate for top-dressing or amending soil.
Enter a bulk price to estimate cost.
You need
0.31cu yd
- Cubic feet
- 8.3 cu ft
- Cubic yards
- 0.31 cu yd
- Bags (1 cu ft)
- 9 bags
- Weight
- ≈ 0.17 tons
Bulk is sold by the yard — order 0.5 cu yd to have enough.
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How it's calculated
- 1
Measure your bed
Enter the length and width in feet (or switch to a circle, or type the square footage directly).
- 2
Pick a mode and depth
Top-dress applies a thin layer on top (default 1 inch). Amend-bed mixes compost into the existing soil — set the soil depth to amend and the compost ratio (default 30%).
- 3
Read your result
Volume is area × depth ÷ 12 for cubic feet, ÷ 27 for cubic yards, and ÷ your bag size (rounded up) for bags.
Frequently asked questions
How much compost do I need per square foot?
For a 1-inch top-dressing, every 100 sq ft needs about 8.3 cubic feet of compost (100 × 1 ÷ 12). At 2 inches, double it.
Can you use too much compost?
Yes. As an amendment, 1–2 inches worked into the top 6–8 inches per year is plenty. Beds more than about one-third compost can hold too much water and run high in salts and phosphorus.
Compost vs topsoil for raised beds?
Compost feeds plants but is too light to fill a bed alone. A common raised-bed mix is roughly 60% topsoil, 30% compost, 10% aeration — see the Raised Bed Soil Calculator.