What is fill dirt?
Fill dirt is subsoil taken from below the topsoil layer. It has little organic matter, so it does not rot or sink much over time. That makes it right for filling holes, building up ground and backfilling around foundations. It is not good for growing plants.
Planning the rest of the job? Use the Dirt calculator and the Sand calculator too.
Why add extra for compaction?
Loose fill takes up more space in the truck than it does once it is tamped down. Plan on ordering 15 to 25% more than the hole measures. The calculator adds 20% when the box is ticked.
How does the calculation work?
Volume (m³) = area (m²) × depth (m) × 1.2
A low corner 5 m by 4 m that needs raising 30 cm: 20 × 0.3 = 6 m³. With 20% for compaction, order 7.2 m³, roughly 10 tonnes.
If the depth varies, measure it in several places and use the average. For a hole with sloping sides, measure the width halfway down.
How is fill dirt sold?
Fill dirt is almost always delivered loose and priced per cubic metre or per tonne. It is one of the cheapest bulk materials, so delivery often costs more than the dirt. Ask how much one truck carries so you can order full loads.