What is the Concrete Weight Calculator?
This tool estimates how much a slab, footing, column or any rectangular concrete pour will weigh. Knowing the weight matters for structural loading, transport logistics, crane and formwork capacity, and for planning how much demolition debris you'll haul away. The calculator works in both metric (meters → kilograms) and imperial (feet → pounds) units.
How to use it
Enter the length, width and thickness (depth) of your pour in consistent units, then choose the unit system. The default density is the standard value for normal-weight cured concrete: 2400 kg/m³ (about 150 lb/ft³). If you are using lightweight, high-density or aggregate-specific concrete, you can override the density field with your own value.
The formula explained
The math is two steps. First compute the volume: \( V = \text{Length} \times \text{Width} \times \text{Thickness} \). Then multiply that volume by the density of the material: \( \text{Weight} = V \times \rho \). Density is mass per unit volume, so volume (m³) × density (kg/m³) yields mass in kilograms. The same logic applies in imperial units with ft³ and lb/ft³.
$$\text{Weight (kg)} = \text{Length (m)} \times \text{Width (m)} \times \text{Thickness (m)} \times \text{Density (2400 kg/m}^3)$$
$$\text{Weight (lb)} = \text{Length (ft)} \times \text{Width (ft)} \times \text{Thickness (ft)} \times \text{Density (150 lb/ft}^3)$$
Worked example
A patio slab 3 m long, 3 m wide and 0.1 m thick has a volume of \( 3 \times 3 \times 0.1 = 0.9 \) m³. At 2400 kg/m³ that is $$0.9 \times 2400 = 2160 \text{ kg}$$ or 2.16 tonnes. A crew can plan equipment and transport around that figure.
FAQ
Why 2400 kg/m³? It's the accepted average for standard reinforced and plain normal-weight concrete; real mixes range roughly 2300–2500 kg/m³.
Does this include rebar? No — it estimates the concrete only. Steel reinforcement adds a small additional weight (steel is ~7850 kg/m³).
How do I weigh an irregular shape? Break it into rectangular sections, calculate each separately, and add the weights together.
