Work out what concrete weighs from its volume. A cubic yard is about 4,050 lb and a cubic metre about 2.4 tonnes, with lightweight mixes covered.
Weight matters for access, formwork and lifting, not for ordering.
Enter a volume to see what it weighs.
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weight = volume × density
Normal-weight concrete runs about 150 lb per cubic foot, or 2,400 kg per cubic metre. A cubic yard is 27 cubic feet, so a yard weighs roughly 27 × 150 = 4,050 lb — a little over two short tons.
Worked example: A 5 cubic yard pour weighs about 20,250 lb, or just over 10 short tons. In metric, 4 m³ is about 9,600 kg.
Concrete is ordered by volume and billed by volume, so its weight rarely comes up until it matters a great deal — when a truck has to cross a lawn, when formwork has to hold it up, or when a slab is going on a suspended floor. The arithmetic is simply volume times density; the useful part is knowing which density to use and what the number implies.
| Volume | Normal-weight concrete |
|---|---|
| 1 cubic foot | 150 lb |
| 1 cubic yard | 4,050 lb (2.03 short tons) |
| 1 cubic metre | 2,400 kg (2.4 tonnes) |
| 5 cubic yards | 20,250 lb (10.1 short tons) |
| 10 cubic yards | 40,500 lb (20.3 short tons) |
| Mix | Density | Per cubic yard |
|---|---|---|
| Lightweight | 110 lb/ft³ (1,760 kg/m³) | 2,970 lb |
| Normal weight | 150 lb/ft³ (2,400 kg/m³) | 4,050 lb |
| Reinforced | 156 lb/ft³ (2,500 kg/m³) | 4,212 lb |
Normal weight covers essentially all ordinary slabs, footings and driveways. Lightweight mixes swap the aggregate for expanded shale or clay and are used where dead load matters, such as toppings on suspended floors — they cost more and are specified deliberately, not chosen by accident. Reinforced is a little heavier simply because steel is much denser than aggregate.
Freshly placed concrete is what these figures describe. A cured slab weighs marginally less, since some mix water is consumed by hydration and some evaporates, but the difference is a few percent and not worth planning around.
Truck access. This is the big one. A mixer carrying 8 to 10 cubic yards has roughly 16 to 20 tons of concrete aboard, and the truck adds another 15 to 20 tons. That combined load is what cracks existing driveways, crushes kerbs and drops through septic tank lids and service covers. Walk the route before pour day and tell the supplier about anything soft, and about any bridge, cattle grid or private culvert on the way in.
Formwork and propping. Wet concrete behaves like a dense liquid and pushes outward on forms, especially in deep pours and columns filled quickly. Pressure grows with pour rate and height, which is why tall forms are filled in lifts.
Suspended slabs and toppings. Adding concrete to an existing floor adds dead load permanently. That is a structural question, not a DIY one.
Lifting. A precast lintel, step or paver has to be moved by someone. At 150 lb per cubic foot, small elements get heavy fast — a 2 ft × 2 ft × 4 in slab is about 200 lb.
Concrete is bought by the cubic yard or cubic metre, not by weight, so nothing here changes what you order. Use the cubic yard calculator for volume, and treat weight as a planning number for access, formwork and lifting.
Get the volume first with the cubic yard calculator, or convert an existing figure with the cubic feet to cubic yards converter. For small pours, the concrete bag calculator turns volume into bags — worth knowing that an 80 lb bag makes only about 0.6 cubic feet, so a cubic yard is around 3,600 lb of bags to carry. Price the job with the concrete cost calculator.
Pouring a different shape? These cover the rest of the common jobs.
Calculate the concrete volume for a rectangular slab from length, width and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Calculate the concrete volume for a circular slab from diameter and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Calculate the concrete volume for an irregular slab from a pre-measured area and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Calculate the concrete volume for a circular column from diameter and height. Imperial and metric units, with a 10% waste buffer per ACI 318.
Calculate the concrete volume for fence-post holes — by hole, total across all holes, with post-profile displacement and a 10% waste buffer.