Concrete weighs around 2,400 kg per cubic metre (150 lb/ft³), so even a small slab weighs tonnes. You need the weight to check a suspended floor, plan demolition and disposal, size a crane or forklift, or estimate the number of truck loads to haul away broken concrete.
How to use the Concrete Weight Calculator
- Material
- Custom density
- Shape
- Length (or diameter)
- Width
- Thickness / depth
- Quantity
- Every result field is editable: type into Weight of one piece or any other result and Thickness / depth plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
The calculator finds the face area of the shape, multiplies by the thickness for the volume and by the material density for the weight. The weight per unit area is handy for checking floor, shelf or wall loads.
Densities used
| Material | kg/m³ | lb/ft³ | kg/m² per mm |
|---|---|---|---|
| Normal-weight concrete | 2,400 | 149.8 | 2.40 |
| Reinforced concrete | 2,500 | 156.1 | 2.50 |
| Plain concrete (no rebar) | 2,300 | 143.6 | 2.30 |
| Lightweight structural concrete | 1,850 | 115.5 | 1.85 |
| High-density concrete | 3,500 | 218.5 | 3.50 |
| Autoclaved aerated concrete (AAC) | 600 | 37.5 | 0.60 |
| Fresh (wet) concrete | 2,450 | 152.9 | 2.45 |
Tips for an accurate estimate
- Measure the formwork, not the drawing – forms bulge and subgrades are rarely perfectly flat, so add 5–10%.
- Below about 1 cubic yard, premixed bags are usually cheaper; above that, ready-mix saves time and gives a more consistent pour.
- Order ready-mix in quarter- or half-yard steps and ask about short-load fees for small deliveries.
- Keep fresh concrete damp for at least a week – curing matters as much as the mix for final strength.
Common mistakes to avoid
- Running short mid-pour, which leaves a weak cold joint.
- Adding extra water on site to make concrete easier to place – it lowers strength and increases cracking.
- Ignoring the volume of rebar, posts or pipes in the pour, or the gravel base under it.
Inputs explained
| Field | What to enter |
|---|---|
| Material | Choose one: Normal-weight concrete, Reinforced concrete, Plain concrete (no rebar), Lightweight structural concrete … |
| Custom density | Units: kg/m³, lb/ft³, g/cm³, lb/yd³ |
| Shape | Choose one: Rectangle / square, Circle (length = diameter), Right triangle |
| Length (or diameter) | Units: m, ft, cm, in, yd |
| Width | Units: m, ft, cm, in, yd |
| Thickness / depth | Units: in, cm, mm, ft, m |
| Quantity | A number |
Formula
Weight = area × thickness × density × quantityArea: rectangle L × W, circle π D² ÷ 4, triangle L × W ÷ 2Worked example
Inputs — Material: Normal-weight concrete; Custom density: 2,400 kg/m³; Shape: Rectangle / square; Length (or diameter): 3 m; Width: 3 m; Thickness / depth: 3.93701 in; Quantity: 1.
Results — Area of one piece = 9 m²; Volume of one piece = 900 L; Weight of one piece = 2,160 kg; Total weight = 2,160 kg; Weight per unit area = 240 kg/m².
Frequently asked questions
How much does a cubic yard of concrete weigh?
About 4,050 lb (2 US tons) for normal-weight concrete.
How much does a 4-inch concrete slab weigh per square foot?
About 50 lb/ft² (240 kg/m²).
How much does wet concrete weigh compared with cured concrete?
Fresh concrete is slightly heavier (≈ 2,450 kg/m³) because some water evaporates as it cures.
What formula does the Concrete Weight Calculator use?
Weight = area × thickness × density × quantity.