Slab volume uses three dimensions
A 5 m by 3 m rectangle is 15 m². A 10 cm thickness must become 0.10 m before multiplication, giving 1.5 m³. Leaving depth as 10 would create a result one hundred times too large. Concrete is ordered by volume, so consistent metre units are the first check.
Depth follows the finished design
The depth belongs to the compacted and formed slab, not an optimistic average measured over loose ground. A shallow depression, a slope, or reinforcement cover can alter the real volume materially. Take levels or divide an irregular area into sections rather than relying on one depth taken at an edge.
Fresh concrete has practical losses
Spillage, over-excavation, pump priming, and uneven sub-base mean a perfect geometric volume may be short on site. Ready-mix suppliers also use their own delivery increments. Decide an allowance with the contractor or supplier rather than treating 1.500 m³ on a screen as an exact truck load.
Strength is not calculated here
Cubic metres do not determine mix class, reinforcement, curing, joint spacing, frost protection, or bearing capacity. A thin decorative pad and a structural footing can have the same volume but completely different engineering requirements. Use approved drawings and local requirements for any load-bearing work.
Appropriate use
Use the figure to check a rectangular pour before requesting a quote. It cannot inspect excavation, decide whether concrete may be placed in the weather, or approve a foundation. Record length, width, and compacted depth with the result, then confirm the order with the specified mix supplier.
Confirm the pour sequence
A slab pour needs forms, reinforcement position, access for delivery, placement time, finishing tools, and a curing plan in addition to enough cubic metres. Measure form depth at several points after the sub-base is prepared. If a truck load must be split between locations, calculate each pour separately and preserve a margin approved for the job. Volume arithmetic cannot correct a late delivery or an unprepared form.
Inspection note: Confirm the pour sequence
Before ordering or fitting, revisit this project-specific check: A slab pour needs forms, reinforcement position, access for delivery, placement time, finishing tools, and a curing plan in addition to enough cubic metres; Measure form depth at several points after the sub-base is prepared; If a truck load must be split between locations, calculate each pour separately and preserve a margin approved for the job; Volume arithmetic cannot correct a late delivery or an unprepared form.