Landscaping Materials Volume Calculator
Enter area dimensions and depth to get the volume in cubic metres, litres, and tonnes. Shows bulk bag counts at 0.5m³, 0.75m³, and 1m³ bag sizes. Nothing uploaded.
Area & Depth
Material Required
Learn more: landscaping materials volume and bulk bag ordering
The core calculation - converting area and depth to cubic metres and weight
Volume is length (m) × width (m) × depth (m). For a 5m × 3m area at 100mm (0.1m) deep: 5 × 3 × 0.1 = 1.5m³. Each material has a different density: gravel is roughly 1.5 tonnes per m³, topsoil is roughly 1 tonne per m³ (wet). Multiply your volume by the material density to get the total weight. The calculator uses standard published densities for each material type to give you accurate tonne estimates.
Gravel depth guidance - decorative paths, driveways, and borders
For decorative gravel paths, 40-50mm depth allows the gravel to move slightly under foot, reducing displacement over time. For driveways, lay 75-100mm over a compacted sub-base to handle vehicle weight without creating ruts. Plant borders and mulch areas need 50mm minimum to suppress weeds and retain soil moisture. The calculator accepts any depth from 1mm to 1m, so you can experiment with different depths to see the impact on volume and cost.
Bulk bag sizing and under- or over-ordering - getting the exact amount
Standard bulk bags come in 0.5m³, 0.75m³, and 1m³ sizes. The calculator shows how many whole bags you need at each size, rounding up so you never under-order. Ordering slightly more than the calculated volume is normal - landscape surfaces settle, and it is better to have leftover material than to make a second trip. Many suppliers will partially fill a final bag, so ask whether that option is available for your job.
FAQ
Why is wet topsoil heavier than dry?
Topsoil density varies by moisture content. Freshly delivered "wet" topsoil can weigh 1.5 tonnes per m³, while dry topsoil might be only 0.8 tonnes per m³. The calculator uses a standard 1 tonne/m³ figure - if you know your supplier's soil is notably wetter or drier, ask them for their density and do a quick manual calculation.
Do I need to add extra for settling or compaction?
Most landscape materials (gravel, bark) compress by 10-20% after settling. Topsoil compresses less (5-10%). Adding 10-15% to your calculated volume gives you a safety margin - this is why the calculator rounds up to the next whole bag.
Can I use this for paving sand or bedding sand?
Yes. Enter your area, the depth you plan to lay (typically 25-50mm for a sand bed under pavers), select "Sand" from the material dropdown, and get your volume and bag count.