Concrete quantity and materials planner
Concrete Calculator
Plan concrete for slabs, footings, walls, columns, post holes, stairs and curbs. Combine several pours, add waste, estimate bags or ready-mix, reinforcement, weight and total cost.
Build your concrete project
Add every concrete section as a separate item. The calculator combines their net volumes before applying the waste allowance.
Your concrete order and material estimate
–m³Live project profile
The diagram follows the currently selected concrete section. It is illustrative and not a construction drawing.
Volume by project section
Supply and price
Planning estimate only. Confirm dimensions, ground conditions, concrete specification, reinforcement, load-bearing requirements, delivery minimums and final quantities with your engineer, contractor or concrete supplier before ordering or building.
How dimensions become an order quantity
The calculator converts every section to cubic metres, combines the net volumes and then applies the selected waste percentage. Results are also shown in cubic yards, cubic feet and litres.
Choosing bagged concrete or ready-mix
Bagged concrete is convenient for small repairs and post holes. Larger pours are usually easier to schedule as ready-mix. Always use the product’s stated yield rather than estimating yield from bag weight alone.
Choosing an extra-concrete allowance
Simple, accurately formed slabs may need less extra material than irregular excavations, deep footings or pours with difficult access. Unused concrete cannot always be returned.
Reinforcing concrete requires structural design
The optional bar and mesh figures are quantity-planning aids only. They do not determine whether reinforcement is required or what diameter, grade, spacing, lap or cover is safe.
Volume formulas used
Placement and curing checklist
- Verify form dimensions and excavation depth at several points.
- Plan access, placement sequence and enough labour before the truck arrives.
- Do not add water beyond the mix supplier’s instructions to make placement easier.
- Protect fresh concrete from rapid drying, freezing and heavy rain.
- Follow the specified curing method and loading schedule for the project.
- Confirm local code, permits and underground-service locations before excavation.
Concrete Calculator FAQ
How is concrete volume calculated?
Rectangular sections use length multiplied by width and depth. Round columns and post holes use pi multiplied by radius squared and depth. The calculator adds all sections together.
How much extra concrete should I order?
A waste allowance helps cover uneven excavation, form variation, spillage and finishing. The appropriate percentage depends on site conditions and the type of pour.
Should I order bags or ready-mix concrete?
Bags suit many small jobs, while larger or continuous pours are often more practical with ready-mix. Compare total quantity, access, labour, delivery minimums and working time.
Can bag count be calculated from bag weight?
Not reliably. Products with the same bag weight can have different cured yields. Use the volume yield printed by the manufacturer on the exact product.
How much does concrete weigh?
Normal-weight concrete is often estimated near 2,400 kg per cubic metre, but the actual density depends on the specified mix and aggregate. The density field can be adjusted.
Does the result include reinforcement?
Concrete volume and reinforcement quantities are reported separately. The optional reinforcement estimate is for purchasing guidance and is not a structural design.
How does the stair calculation work?
The calculator models a solid staircase as a stack of equal rectangular steps. Landings, supports, voids and custom profiles should be entered as additional sections or checked separately.
Can I combine several slabs and footings?
Yes. Add each pour or shape as a separate section. The results show every section’s volume and the combined order quantity.