Related Resources
Concrete Quantity Calculator — How Much Concrete Do You Need?
Calculate exact concrete quantities for any pour — footings, slabs, paths, driveways, and retaining walls. Results in cubic metres with bag estimates.
Frequently Asked Questions
How do you calculate concrete quantity?
Multiply length x width x depth (all in metres) to get cubic metres. For irregular shapes, break them into rectangles and add the volumes together. Always add 5-10% for waste and uneven ground.
How many 20kg bags of concrete make 1 cubic metre?
Approximately 108 bags of 20kg pre-mixed concrete make 1 cubic metre. Each 20kg bag makes roughly 0.009m³. For anything over 0.5m³, it is much cheaper to order pre-mixed delivery.
What strength concrete do I need?
N20 (20 MPa) for paths, driveways, and shed slabs. N25 for house slabs and suspended slabs. N32 for structural footings and commercial. N40 for high-stress structural applications.
Need more than a calculator?
Built Simple does estimating, scheduling, time tracking, and team management — all in one app.
Related Calculators
- Holes Calculator
- Concrete Volume Calculator
- Concrete Cost Calculator
- Concrete Block Calculator
- Concrete Bags Calculator
Helpful Guides
New on Built Simple
- Pier & Beam Footing Calculator — concrete + steel for pier-and-beam slabs.
- Concrete Pier Calculator — individual pier volumes.