Published by BuildCalculators Editorial · Updated 1 October 2026
Measure internal pour dimensions
For a rectangular slab, multiply length × width × depth. Use the finished concrete depth, in consistent units. Break an L-shaped path into two rectangles and total them. The calculator can then convert that volume into cubic metres, cubic yards or an approximate bag count.
Bagged concrete or ready-mix?
Bagged concrete can suit small repairs and modest pads where mixing access is easy. Larger volumes can be difficult to mix consistently and place before the material begins setting. Compare the calculated volume with delivery minimums, access, labour and the product yield printed on a bag.
Plan the base and conditions
Concrete does not fix an unstable base. Project-specific excavation, sub-base, reinforcement, formwork, drainage and joint requirements depend on the load, ground and climate. Avoid pouring in unsuitable weather or onto frozen, waterlogged or poorly prepared ground.
Order with care
A modest allowance can account for uneven ground and losses, but over-ordering concrete creates a disposal problem. Confirm the final amount, chute access and wash-out requirements before a delivery arrives.
This guide is not structural design advice. Footings, retaining structures, driveways and load-bearing work should be specified for the actual site.