Category
Concrete Calculators
Work out how much concrete to order before you pour. These calculators convert your dimensions into cubic yards or cubic metres, add a waste allowance and estimate how many pre-mixed bags you would need based on the yield printed on the bag.
Which calculator do I need?
- Concrete Calculator
- Enter the shape and size of your pour to get the concrete volume in cubic yards and cubic metres, plus how many pre-mixed bags it would take.
- Concrete Slab Calculator
- Work out exactly how much concrete a rectangular slab needs — for a patio, shed base, walkway or garage pad — and compare bagged mix with ready-mix.
- Concrete Bag Calculator
- Find how many bags of pre-mixed concrete a job needs, using the yield from your bag label, and compare bag sizes side by side.
- Cubic Yard Calculator
- Turn any length × width × depth into cubic yards, cubic feet and cubic metres — the units bulk materials are actually sold in.
Before you order concrete
Measure inside the formwork once it is built, not from the original sketch, and check the depth in several places: small differences in thickness add up quickly over a slab. Keep every dimension in the same unit before multiplying, and add a waste allowance — most estimators use 5–10 %.
The calculators tell you how much concrete you need, not how strong or thick it must be. Slab thickness, reinforcement, footing size and mix strength depend on the loads, the ground and your local building rules, so take those from your plans or a qualified professional.
- Small jobs such as post holes and repairs suit pre-mixed bags; for about a cubic yard (0.75 m³) or more, ready-mix delivery is usually more practical.
- Plan access, labour and tools so you can place and finish the whole pour before it starts to set.
- Wet cement is alkaline and can burn skin: wear gloves, eye protection and long sleeves, and follow the safety advice on the bag.