Compost Calculator

Compost is bought by the cubic yard, so the tool works in volume: bed length times width gives the area, and multiplying by the depth turns that area into a volume. Depth is entered in inches while the bed is measured in feet, so the depth is divided by twelve to reach cubic feet, then by twenty-seven to reach the cubic yards a supplier quotes.

A delivery weight in tons comes alongside the volume, using a finished-compost bulk density near `1,000` kilograms per cubic meter — about `0.84` US tons per cubic yard at typical delivery moisture. Compost weight is even less predictable than soil because it depends heavily on how wet and how finished the material is, so order by the yard and treat the ton figure only as a guide to how heavy the load will be.

How deep to go depends on the job. Top-dressing an established bed wants a thin `1` to `3` inch layer worked into the surface, while filling or heavily amending a new bed can take `4` inches or more. Because coverage scales directly with depth, that field is the one to double-check before ordering.