Estimate concrete for slabs, footings and fence posts. Enter the dimensions to get the volume in cubic metres plus the number of bags to buy.
Bag counts assume 20 kg bags yielding about 0.01 m3 each. Add 5-10% extra for uneven ground and spillage.
How to Use
- Enter the length, width and depth (thickness) of the area.
- Choose metres or feet as your unit.
- Press Calculate concrete.
- Read the volume in cubic metres, cubic feet and cubic yards, plus the bag count.
Key Features
- Metres or feet — enter dimensions in whichever unit suits you.
- Three volume units — cubic metres, cubic feet and cubic yards together.
- Bag counts — converts volume into 20 kg bags to buy.
- Slabs, footings, posts — works for any rectangular pour.
- 100% private — runs entirely in your browser; nothing is sent or stored.
FAQs
How many bags are in a cubic metre?
About one hundred 20 kg bags, since each bag yields roughly 0.01 m3 of mixed concrete.
Should I order extra?
Yes — add 5 to 10% extra for uneven ground, spillage and formwork gaps.
What depth should a patio slab be?
Garden slabs are typically 75 to 100 mm thick; driveways usually need 100 to 150 mm. Check local guidance for structural work.
Does this cover circular areas?
Not directly — for a round pad, work out the area (pi x radius x radius) and multiply by depth yourself, or use our Area Calculator first.
Is my data sent anywhere?
No. The calculation runs entirely in your browser and never transmits or saves your entries.
Related Tools
Try these related tools: Volume Calculator, Area Calculator and Unit Converter.