🧱 Construction
Concrete Weight Calculator
Enter a volume and a mix type to get its weight in kilograms, tonnes and pounds — and see why a full concrete truck runs out of payload long before it runs out of drum.
How much does concrete weigh?
Normal structural concrete weighs about 2,400 kg per cubic metre, which is 4,050 lb per cubic yard, or 145 lb per cubic foot. That figure is for cured concrete made with ordinary gravel or crushed-stone aggregate. Reinforced concrete is slightly heavier at roughly 2,500 kg/m³ because the steel adds mass without adding much volume, and lightweight concrete made with expanded clay or pumice drops to about 1,850 kg/m³.
The practical consequence is that concrete is ordered by volume and paid for by volume, but transported under a weight limit. A standard drum holds 6 to 8 m³, yet a 6 m³ load of normal concrete already weighs 14.4 tonnes. Add the truck's own 12 to 15 tonnes and you are at the legal limit of a three-axle vehicle, which is why sites with tight access get smaller loads at a higher price per cubic metre.
Weight per cubic yard, cubic foot and square metre
Most confusion comes from mixing up volume and area. A slab is quoted in square metres or square feet, but its weight depends on thickness. The table gives the common reference figures so you can check a delivery note or a structural calculation without running the form above.
| Quantity | Normal concrete | Reinforced | Lightweight |
|---|---|---|---|
| 1 m³ | 2,400 kg | 2,500 kg | 1,850 kg |
| 1 yd³ | 4,050 lb (1.84 t) | 4,215 lb | 3,120 lb |
| 1 ft³ | 150 lb (68 kg) | 156 lb | 115 lb |
| 1 m² at 100 mm | 240 kg | 250 kg | 185 kg |
| 1 m² at 150 mm | 360 kg | 375 kg | 278 kg |
Why the density is not a single number
Concrete is aggregate, sand, cement and water, and each of those moves the density. A mix with 20 mm granite aggregate and a low water-cement ratio lands near 2,450 kg/m³; the same mix with a rounded river gravel sits nearer 2,300. Air entrainment, used for freeze-thaw resistance, removes about 5 percent of the mass. Fresh concrete is also heavier than cured concrete by the weight of the water that later evaporates — roughly 2 to 4 percent over the first month.
For estimating, 2,400 kg/m³ is the right default and is what most ready-mix suppliers quote. If you are checking whether a floor or a trailer can take the load, use the reinforced figure and add the weight of any screed, insulation or services above it.
Working out the weight of a slab or footing
- A 4 m × 3 m patio slab at 100 mm thick is 1.2 m³, so about 2.9 tonnes.
- A strip footing 600 mm wide × 300 mm deep × 12 m long is 2.16 m³, so about 5.2 tonnes.
- A single garage base 6 m × 3 m at 150 mm is 2.7 m³, so about 6.5 tonnes.
If you are mixing by hand rather than ordering ready-mix, convert the weight back into bags: a 25 kg bag of general-purpose concrete mix yields roughly 0.012 m³, so a cubic metre needs about 83 bags. That is the point at which most people stop mixing and phone the plant.