Concrete calculator
Geometric m³ for slabs, strip footings, round columns, walls, solid stairs, ramps, round slabs or ring footings. Pick the shape above; quantity estimation — structural sizing is signed by a qualified professional.
Purchase quantity
3.21 m³
Net measurement: 3 m³ · Waste 7 %
- Net concrete3 m³
- Concrete to order (with waste)3.21 m³
Ready-mix or bags? At this volume: ready-mix truck.
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How it's calculated (visible formula)
slab V=l×w×t; footing V=l×w×d; column V=πr²h; wall V=l×h×t; stairs V=n×(tread×riser/2)×w; ramp V=(l×h/2)×w; round V=πr²×t; ring V=π(R²−r²)×h; order = V×(1+waste)
- Net geometric measurement, no waste.
- Adjustable waste % for cuts and breakage.
- Purchase rounded up to sellable units (boxes, bags, buckets, boards).
Ready-mix or bags? (guide)
| Volume | Recommendation |
|---|---|
| Under 0.5 m³ (~20 bags) | Bags (mix on site) |
| 0.5–1 m³ (20–39 bags) | Bags; price a short load to compare |
| 1–2 m³ | Price both: bags vs short-load ready-mix |
| Over 2 m³ | Ready-mix truck (order extra; pump if needed) |
Worked example: 5×4×0.15 slab
- V = 3 m³
- +7% → 3.21 m³
→ Order 3.5 m³ from the plant (round up).
Common mistakes
- Ordering exact m³ with no plant margin.
- Forgetting pumping, formwork and rebar.
- Mixing m³ with m².
From calculation to quote
Add labour, overhead and your margin, and generate the professional PDF.
FAQs
- Ready-mix or site-mixed?
- Above ~1–2 m³ ready-mix usually pays off in consistency; this page estimates volume either way.
- How many 50 kg bags in 1 m³?
- A 50 kg bag yields ~26 l: 1 m³ needs about 39 bags. That's why above ~1 m³ it's worth pricing ready-mix.
- Rebar included?
- No: this calculator only cubes concrete.
- Does it handle footings, stairs and ramps?
- Yes — choose the shape above: strip footing, stairs by steps, ramp by length and rise, round slab by diameter, or ring by diameters.
Maintained by Srikanta M · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.