Concrete Calculator UK
Estimate the volume of concrete you need for a slab or footing, in cubic metres, feet and yards.
How it works
Enter the length, width and thickness of the slab and how many you are pouring. The calculator returns the volume in cubic metres, feet and yards, adds a 10% waste allowance, and can estimate bags if you provide the yield per bag.
Frequently asked questions
How do I calculate concrete volume?
Multiply length × width × thickness in consistent units. The tool does this and converts to cubic metres, feet and yards.
How many bags of concrete do I need?
It depends on the bag’s yield. Enter the yield per bag (in m³) and the calculator divides the total volume to estimate the number of bags.
Why add a waste allowance?
Some concrete is always lost to spillage, uneven sub-base and over-excavation, so a 10% margin is a sensible default.
Concrete Calculator
Plan a pour with confidence: enter the slab dimensions and get the concrete volume in three units, plus a waste allowance and an optional bag estimate.
Tips
- Thickness is entered in centimetres (metric) or inches (imperial).
- A 10% waste allowance covers spillage and uneven ground.
- Bag yield varies by product — check the bag and adjust the yield field.
Results are estimates for general guidance in United Kingdom and may not reflect the latest local rates, fees or rules. Check official sources before making decisions.