How many cement bags are needed per m³ of concrete?

For standard concrete (250 kg/m³ mix), you need 5 bags of 50 kg per m³. For structural concrete (300 kg/m³), use 6 bags. This calculator uses the typical dosage for each element type.

Why should I add a wastage percentage?

On-site losses from spillage, unusable mixes and level corrections always occur. Adding 5–10 % to your final order ensures you don't run short of material.

What is the difference between mass concrete and reinforced concrete?

Mass concrete has no steel reinforcement and is used for low-load foundations. Reinforced concrete includes steel bars that provide tensile strength, making it suitable for slabs, columns and beams.

Concrete Beam Calculator

Last updated: 2026-05-09

Use the Concrete Beam Calculator to get instant, accurate results. Enter your values below.

Inputs

Dimensions

Beam width (m) (m)

Beam depth (m) (m)

Beam length (m) (m)

Quantities & Type

Number of beams

Wastage Allowance (%)

Result

Enter values and press Calculate

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Common Sizes — Click to Fill

	Beam width (m) (m)	Beam depth (m) (m)	Beam length (m) (m)	Number of beams (ud)
Caso 1	0.1 m	0.2 m	2.0 m	1.6 ud
Caso 2	0.17 m	0.35 m	3.5 m	2.8 ud
Caso 3	0.25 m	0.5 m	5.0 m	4.0 ud
Caso 4	0.38 m	0.75 m	7.5 m	6.0 ud
Caso 5	0.62 m	1.25 m	12.5 m	10.0 ud

Popular combinations

Concrete Beams 0.2×0.4m Section 3m Long – 2 Concrete Beams 0.2×0.5m Section 3m Long – 4 Concrete Beams 0.2×0.6m Section 4m Long – 2 Concrete Beams 0.25×0.5m Section 5m Long – 4 Concrete Beams 0.25×0.6m Section 5m Long – 6 Concrete Beams 0.3×0.4m Section 6m Long – 4 Concrete Beams 0.3×0.5m Section 8m Long – 4 Concrete Beams 0.3×0.6m Section 8m Long – 6

What is a Concrete Beam?

A concrete beam is a horizontal structural element that carries loads from slabs and transfers them to columns. Beams resist bending and shear forces. This calculator estimates concrete volume, steel reinforcement and formwork for rectangular beams.

Calculation Method

Volume per beam = Width × Depth × Length

Steel density varies by span and load: typical values are 100-150 kg/m³ for beams. Formwork area includes both sides and the bottom of each beam.

Worked Example

4 beams 0.25m × 0.50m × 5m:

Volume per beam = 0.25 × 0.50 × 5 = 0.625 m³
Total concrete = 0.625 × 4 = 2.5 m³
Cement = 2.5 × 7 = 18 bags (50 kg)
Steel = 2.5 × 140 kg/m³ = 350 kg
Formwork = 2(0.25+0.50) × 5 × 4 = 30 m²

Common Mistakes

Incorrect depth-to-span ratio leading to excessive deflection
Placing tension steel in the wrong zone (must be at bottom for simply supported beams)
Insufficient anchorage length at beam supports
Not providing enough shear reinforcement (stirrups)

Standards

Calculated per EN 1992-1-1.

Written and reviewed by the CalcToWork editorial team. Last updated: 2026-05-09.