Part of the topic: 🏠 Home, energy & car
Concrete calculator (m³ & bags)
Choose a rectangular slab/foundation or round holes, enter the dimensions and the bag yield from the packaging.
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🔒 Runs entirely in your browser – nothing you enter is uploaded or stored.
How to use it
- Choose the shape and enter the dimensions in metres (holes: diameter in cm).
- Add a waste allowance of 5–10 %.
- Enter bag size and yield from the packaging and read the number of bags.
Last checked: October 2026 · Based on: Volume formulas; bag yield per manufacturer's packaging. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
How many bags of concrete for 1 m³?
With 25 kg bags yielding about 12 litres, roughly 84 bags – check the yield on your product.
How thick should a garden slab be?
For paths or a shed often 10–15 cm on a compacted gravel base; follow the structural requirements for heavier loads.
Bags or ready-mix truck?
For more than about 1 m³ a ready-mix delivery is usually cheaper and faster.