Volume alone tells you nothing — you need the density
A cubic meter is a fixed box of space; how much it weighs depends entirely on what fills it. Water is the reference: 1 m³ weighs exactly 1 tonne, which is where the "1000 kg/m³" comes from. Look up your material's density, then it is one multiplication.
The same box, very different weight
One cubic meter of each material, drawn to scale against steel. This is why "a cubic meter" is never a weight on its own.
Steel packs almost 8 times the mass of water into the same space; concrete about 2.4 times.
Density of common materials
| Material | Density (kg/m³) | 1 m³ weighs |
|---|---|---|
| Water | 1000 | 1.00 t |
| Dry sand | 1500 | 1.50 t |
| Wet sand | 1600 | 1.60 t |
| Gravel (loose – packed) | 1500–1700 | 1.50–1.70 t |
| Topsoil (dry – wet) | 1300–1600 | 1.30–1.60 t |
| Concrete | 2300–2400 | 2.30–2.40 t |
| Steel | 7850 | 7.85 t |
Loose materials settle. Order 5–10% extra volume for sand, gravel and soil to allow for compaction and spillage.
Which tonne — and why it matters on a shipping ticket
- Metric tonne is 1000 kg. This is the default here and the standard almost everywhere outside the US.
- US short ton is 907.185 kg (2000 lb), so it is about 10% lighter. 1 metric tonne = 1.102 short tons.
- Moisture and packing shift the density, not the formula. Weigh a sample if a delivery has to hit an exact figure.
Common questions
How do I convert cubic meters to tonnes?
Multiply the volume in cubic meters by the material density in kg per cubic meter, then divide by 1000. For 5 cubic meters of sand at 1500 kg/m3: 5 x 1500 / 1000 = 7.5 tonnes.
Does 1 cubic meter always weigh 1 tonne?
Only for water. One cubic meter of water is 1 tonne because the metric system was built around it. Everything else depends on density: a cubic meter of concrete is about 2.4 tonnes, and a cubic meter of steel is nearly 8 tonnes.
Why does wet sand weigh more than dry sand?
Water fills the gaps between the grains, so it adds mass without adding much volume. Dry sand is about 1500 kg/m3; at 20 percent moisture it climbs to roughly 1600 kg/m3. The same applies to soil and gravel.
