Topsoil Volume Calculator — Calculate Soil m³ and Tonnes
Plan topsoil from the actual planting area and intended average depth, then convert the volume to estimated tonnes and bag-equivalent units.
Topsoil quantity inputs
Topsoil volume formula
Planning volume = net volume × (1 + allowance ÷ 100)
Convert the entered depth from millimetres to metres before multiplying by area.
Average depth versus detailed takeoff
A single average depth is useful for straightforward beds, but large changes in grade or finished level can make one average misleading. For better control, split the project into measurable zones and add the resulting volumes.
Mass is optional and density-dependent
Volume is geometric. Mass is a conversion that depends on bulk density. Topsoil can change in mass per cubic metre with moisture, texture and compaction, so use a supplier-specific value when available.
Worked example
120 m² at 200 mm gives 24 m³ net. A 10% allowance produces 26.4 m³. At 1,600 kg/m³, estimated planning mass is 42.24 tonnes.