Landscaping
Soil Calculator
Convert garden bed area and depth into cubic metres and tonnes of soil.
How this calculator works
Measure your bed or lawn area, either as length by width, a total area, or a circle diameter. The calculator multiplies area by your chosen depth to get cubic metres, then adds 10 percent because soil settles and compacts once spread and watered.
Weight matters for delivery, so the calculator also converts volume to tonnes using a density for your soil type. Garden soil runs about 1.2 to 1.3 tonnes per cubic metre, sandy loam closer to 1.4.
For small jobs it compares bagged soil against bulk delivery. Bulk is almost always cheaper past about half a cubic metre.
| Use | Depth | Notes |
|---|---|---|
| New garden beds | 100mm to 300mm | Deeper for vegetables and shrubs |
| Topdressing a lawn | 10mm to 20mm | Grass must poke through |
| Turf underlay | 100mm | Screened sandy loam |
| Raised planter boxes | 300mm plus | Fill cheap, top with quality mix |
| Soil type | Density | Weight of 1m³ |
|---|---|---|
| Soil and compost mix | 1.2 t/m³ | about 1,200kg |
| Garden soil | 1.25 t/m³ | about 1,250kg |
| Screened topsoil | 1.3 t/m³ | about 1,300kg |
| Sandy loam | 1.4 t/m³ | about 1,400kg |
Moisture changes weight noticeably. Wet soil can weigh 10 to 20 percent more.
Frequently asked questions
How much does a cubic metre of soil cover?
One cubic metre covers 10 square metres at 100mm deep, or 20 square metres at 50mm. Divide 1,000 by your depth in millimetres to get coverage in square metres.
How heavy is a cubic metre of soil?
Between 1.2 and 1.4 tonnes depending on type and moisture. That is well beyond a standard box trailer rated at 750kg, so most people get soil delivered or make several trips.
Should I buy soil in bags or bulk?
Under about half a cubic metre, bags are convenient and avoid delivery fees. Beyond that bulk wins clearly: bagged soil often costs 2 to 3 times more per cubic metre than a bulk delivery.
What depth of soil do I need for turf?
Turf suppliers recommend 100mm of screened sandy loam or turf underlay. Less than 75mm makes the lawn dry out fast and root poorly.
Why add 10 percent extra soil?
Fresh soil is fluffy from screening and settles once spread, watered and walked on. Ordering about 10 percent extra means you will not come up short after the first good soak.
Related calculators
Ready to get this job done?
Tell us about your project and hear from up to 3 local pros within 1 business day. Free and no obligation.