Concrete calculator – volume and cost of foundations
Tick the elements (strip footings, slab, pads, columns, walls), enter the dimensions and get m³ of concrete with allowance, truck loads, indicative ingredients for site-mixed C20/25, reinforcement steel and cost.
1. Concrete elements
2. Options
Result
Net volume
| Element | m³ | steel kg |
|---|
Ingredients for site-mixed C20/25
Indicative recipe per 1 m³: 350 kg CEM II 32.5 cement, 0.5 m³ sand (about 800 kg), 0.75 m³ gravel 2–16 mm (about 1200 kg), about 175 l water. A shopping list, not a mix design – for structural elements order certified ready-mix.
How we calculate
Volume of each element = product of its dimensions (pads and columns × count). Net sum × (1 + allowance) = concrete to order; trucks = volume ÷ capacity rounded up. Steel indicative: slab 80 kg/m³, strip and pad footings 60, columns 120, walls 70 kg/m³. Mass: 2400 kg/m³.
The calculator computes geometric volume. Concrete class, reinforcement and element thicknesses come from the structural design – the steel figure is only an order of magnitude for a preliminary estimate.
How the calculator works – questions and answers
How much concrete do strip footings for a house need?
A 10 × 8 m house with a middle wall has about 44 m of footings. For a 0.6 × 0.4 m footing that is 44 × 0.6 × 0.4 = 10.6 m³ net, about 11.1 m³ with a 5 % allowance – two 8 m³ trucks or one 9 m³ truck plus a top-up. One metre of 0.6 × 0.4 m footing is 0.24 m³.
How many bags of cement per 1 m³ of concrete?
For site-mixed C20/25 (old B25) count about 350 kg of cement per 1 m³, i.e. 14 bags of 25 kg, plus about 0.5 m³ sand and 0.75 m³ gravel. Lean concrete C8/10 under footings needs about 200 kg (8 bags).
How much does 1 m³ of ready-mix cost in 2026?
In Poland ready-mix C20/25 costs roughly 380–480 PLN/m³ net plus delivery (150–300 PLN per truck) and an optional pump (600–1200 PLN/day). Prices depend on region and distance from the plant – enter the rate from your quote.
How much extra concrete should I order?
Usually 5 % for formed slabs and columns and 7–10 % for footings poured straight into the trench (uneven trench walls "eat" concrete). Better to top up than to run dry mid-slab.
How much does 1 m³ of concrete weigh and how much steel is needed?
Normal concrete weighs about 2400 kg/m³ (reinforced about 2500). Indicative steel usage: foundation slabs 60–100 kg/m³, strip footings 40–80, columns 100–150, walls 50–90 kg/m³. Exact quantities and bar sizes come from the structural design.
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