Soil Calculator

What this means

Soil volume is length × width × depth — the same math as a concrete slab, but in smaller depths. We convert the depth (usually in centimetres or inches) to metres before multiplying, add a waste allowance for settling and spillage, and return a cubic volume. Topsoil settles after spreading, so a slightly generous order is standard practice, and knowing the volume lets you compare delivered (bulk) soil against bags by price per cubic unit.

Recommendations

• •Order ~10% extra soil — it compacts and settles noticeably after the first few weeks.
• •For borders and raised beds, mix soil with compost for nutrients, not just bulk.
• •Compare bulk delivery against bagged soil on a per-cubic-metre basis — the difference can be large.

Watch out

• •Soil settles to 10–20% less than the loose volume, so plan the topping-up pass.
• •Quality varies hugely by supplier — for growing, good soil matters more than slightly more volume.