How to Calculate Concrete
What is Concrete?
A concrete calculator determines the volume of concrete needed for slabs, footings, and columns, then converts that to bags of ready-mix or bulk quantities. Concrete is sold by the cubic metre (m³) in bulk or in bags (typically 25kg bags yield ~0.012m³ mixed).
Formula
Step-by-Step Guide
- 1Volume (m³) = Length × Width × Depth (all in metres)
- 2Add 5–10% wastage for uneven surfaces and spillage
- 3Number of 25kg bags = Volume (m³) ÷ 0.012
- 4Typical mix ratio: 1 part cement : 2 parts sand : 3 parts aggregate
Worked Examples
Frequently Asked Questions
What is Concrete?
A concrete calculator determines the volume of concrete needed for slabs, footings, and columns, then converts that to bags of ready-mix or bulk quantities. Concrete is sold by the cubic metre (m³) in bulk or in bags (typically 25kg bags yield ~0
How accurate is the Concrete calculator?
The calculator uses the standard published formula for concrete. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Concrete calculator use?
This calculator works with kilograms, inches, percentages, watts. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Concrete calculator use?
The core formula is: Volume (m³) = Length × Width × Depth (all in metres). Each step in the calculation is shown so you can verify the result manually.
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