Compost Calculator
Estimate compost quantity to amend beds or topdress turf based on coverage area and depth.
Step 1: Units
Step 2
Enter project measurements
Use decimals if needed (e.g. 3.5).
Step 3
How to use this calculator
Measure the coverage rectangle and average depth you want after compaction. Deeper sections can be averaged or split into multiple runs.
What the math is doing
Volume is length × width × depth. Weight multiplies volume by a typical bulk density for that material.
How to measure
Stake the area and run a string line for straight edges. Depth is from existing grade to finished grade.
Frequently asked questions
How much to amend soil?
Common topdress passes are ¼–½ in; deeper mixes are rototilled.
Mature vs fresh compost?
Volume is what matters for hauling; maturity affects plant safety.
Odor and heat?
Hot piles shrink; order closer to spreading if possible.
Municipal source?
Confirm quality and inert content with the producer.