Concrete
Calculate concrete volume and materials
How the calculation works
Add elements (footing, slab, beam, column), enter dimensions and quantity, then pick the concrete class and reserve. The calculator adds up the volumes, applies the reserve, and estimates mass and ingredients for hand mixing.
Formula and assumptions
Volume = length × width × height (round: π × r² × height), summed over all elements. Volume with reserve = volume × (1 + reserve). Mass ≈ volume × 2400 kg/m³. Ingredients per concrete class, e.g. C25/30 = 350 kg cement, 0.5 m³ sand, 0.8 m³ gravel and 180 L water per m³; cement in 25 kg bags, rounded up. Mixes are indicative – structural concrete follows the design and the supplier.
Worked example
Strip footing 10 × 0.4 × 0.5 m = 2 m³; 5 % reserve → 2.1 m³. C25/30: cement 350 × 2.1 = 735 kg → 30 bags × 25 kg; aggregate (0.5 + 0.8) × 2.1 = 2.73 m³; water 180 × 2.1 = 378 L.
What affects real consumption
- Excavation and formwork irregularities increase the real volume.
- Losses in transport, pumping and spillage.
- Aggregate moisture and consistency change the water needed.
Frequently asked questions
How much spare concrete should I order?
5–10 % is typical depending on irregularities and placing method; you choose the reserve in the calculator.
Can hand-mixed concrete be used for structural elements?
Structural elements follow the design and quality requirements; ready-mix concrete delivers a controlled strength class.