How Many Bags of Concrete for 1 Cubic Metre?
One cubic metre is a common reference point for concrete calculations, being the standard unit of measurement for ready-mix orders. Understanding how many bags make up a cubic metre helps you assess project scale and make informed decisions about sourcing.
The Standard Conversion
Boral, one of Australia's leading concrete suppliers, recommends approximately 108 bags of 20kg premix concrete per cubic metre. This figure accounts for typical mixing conditions and the air content of hand-mixed concrete. Other manufacturers may vary slightly, so check bag labelling for specific coverage rates.
Real-World Implications
Consider what 108 bags actually means. That's 2.16 tonnes of material to transport, store, and handle. Each bag requires water addition and mixing, taking approximately 3-5 minutes per bag even with a mixer. The full cubic metre therefore represents 5-9 hours of mixing time alone, plus placement and finishing.
When Bags Make Sense
Bagged concrete suits small projects where you're using well under one cubic metre. The practical limit for most DIYers is around 0.3-0.4 cubic metres, equivalent to 32-43 bags. Beyond this, ready-mix becomes more sensible despite minimum order requirements and delivery fees.
Cost Comparison
At $8.50-12.50 per bag, one cubic metre of bagged concrete costs $918-1,350. Ready-mix concrete typically costs $280-420 per cubic metre plus delivery fees of $100-200. For full cubic metre quantities, ready-mix is almost always more economical, plus it's consistent quality and requires far less labour.
Project Planning
If your project calculates to approximately one cubic metre, seriously consider ready-mix delivery. The time saved, consistent quality, and often lower cost make it the better choice for projects of this scale. Reserve bagged concrete for smaller jobs or situations where truck access is impossible.
Use Our Calculator
Rather than working backwards from volume, use our slab calculator to input your actual dimensions. This gives you precise volume calculations with wastage included, then presents both bag counts and ready-mix options for easy comparison.