Formulas
- Slab: length × width × depth (all in metres)
- Round hole: π × radius² × depth × quantity
Uneven ground and spillage mean you nearly always use more than the exact volume, so a waste allowance of 5–10% is sensible. Ready-mix suppliers sell by the cubic metre; if you are using bagged mix, check the yield printed on the bag.
FAQs
How do I convert mm to metres?
Divide by 1,000. 100 mm = 0.1 m.