Loading page
Concrete volume and bags needed.
The concrete calculator estimates how much concrete you need to fill a slab, footing, footpath, column or any rectangular pour. You enter the length, width and thickness of the pour and it returns the volume in cubic metres, cubic feet and cubic yards.
Knowing the volume up front lets you order the right amount of ready-mix or work out how many bags of dry mix to buy, so you avoid a half-finished pour or paying for concrete you cannot use.
1 m³ ≈ 35.315 ft³ ≈ 1.308 yd³. Feet are converted to metres with ×0.3048 before multiplying. The bag figure reflects the total mix mass, not cement alone.
It shows how many 50 kg bags equal the total wet-concrete mass, which is a quick sizing guide. The real number of cement bags is smaller and depends on your mix ratio — in a 1:2:4 mix, cement is only about one part in seven of the mix.
A typical residential floor or patio slab is 100 mm (4 inches) thick; driveways carrying vehicles are often 125–150 mm (5–6 inches). Always follow your local code or engineer's specification.
Ground is rarely perfectly level, forms flex, and some concrete is lost to spillage. Ordering 5–10% more than the calculated volume avoids running short mid-pour, which can create a weak cold joint.
The calculator does it for you: 1 cubic metre equals about 1.308 cubic yards. Suppliers in some regions price concrete per cubic yard, so this figure is handy when ordering.