CONCRETECALCULATOR
Calculate concrete for slabs and columns. Get cubic metres, bag counts, and ready-mix cost.
Volume
1.2m³
20kg Bags
134
25kg Bags
110
Weight
2.88 t
Ready-mix Est.
£144
What is a concrete calculator?
It calculates the volume of concrete needed for a project and converts it into the number of pre-mix bags or cubic metres for a ready-mix order. Essential for shed bases, patios, garage floors, driveways, and post holes.
How to calculate concrete
For a slab: multiply length × width × depth (in metres). For a column: π × radius² × height.
Choose your shape
Slab for flat pours (patios, floors). Column for post holes and pillars.
Enter dimensions
Use the depth presets for common UK applications.
Read results
Get bags needed and ready-mix volume. Always add 5–10% for waste.
Volume formula
All in metres. 1 m³ concrete ≈ 2.4 tonnes. One 25kg bag covers ~0.011 m³. Ready-mix suppliers typically have a 1 m³ minimum order.
Tips & Best Practices
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Add 10% to your order to allow for spillage and uneven ground
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Ready-mix is more economical above 1 m³ — and saves hours of mixing
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Concrete must be laid on compacted hardcore — never directly on loose soil
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Minimum curing time before use: 24 hours foot traffic, 7 days vehicles
Frequently Asked Questions
Mandeep Singh · 25+ Years UK Financial Services
Important Information
This calculator is for informational purposes only and does not constitute financial advice or a personal recommendation.
Results are estimates based on the information you provide and may not reflect your actual financial position.
You should consider seeking independent professional advice tailored to your specific circumstances before making any financial decision.