Decorative Stone Coverage Calculator — Volume, Tonnes and Bags
Calculate the actual stone volume for a landscape surface, then translate it into estimated tonnes and practical bag quantities.
Stone coverage inputs
m²
mm
kg/m³
%
kg per bag
Bulk density is a material assumption, not a universal constant. Supplier data or a representative project measurement is preferable when available.
Enter area, depth and density, then calculate.
Planning stone mass
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—
—m³
—kg
—Bags
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The quantity model
Net volume = area × depth
Planning volume = net volume × (1 + allowance ÷ 100)
Mass = planning volume × bulk density
Planning volume = net volume × (1 + allowance ÷ 100)
Mass = planning volume × bulk density
Depth is converted from millimetres to metres before calculating the volume.
Volume and mass answer different questions
Volume tells you how much three-dimensional space the stone occupies. Mass tells you how much material must be transported or purchased by weight. The density connects the two.
Depth comparison
60 m² × 40 mm = 2.40 m³
60 m² × 50 mm = 3.00 m³
60 m² × 75 mm = 4.50 m³
60 m² × 50 mm = 3.00 m³
60 m² × 75 mm = 4.50 m³
At a fixed area and density, increasing depth increases required mass in direct proportion.
Worked example
60 m² at 50 mm gives 3.00 m³ net. With 7% allowance, planning volume is 3.21 m³. At 1,600 kg/m³, estimated mass is 5.136 tonnes, or 257 bags of 20 kg.