For transportation purposes, people need to know how much a given volume of material weighs. On a large scale, this means converting the number of cubic metres of material into metric tons. However, a cubic metre of water has a different weight than a cubic metre of granite or feathers, so an estimated density is necessary to establish the weight per volume. To determine metric tons, multiply the density in metric tons per cubic meter by the volume in cubic metres.
Obtain the density of the material by calling the manufacturer or reading reference materials. For example, olive oil has a density of 920 g per litre (2 pounds per litre).
Convert the density into metric tons per cubic meter or the equivalent grams per cubic centimetre. If the known density is already in one of these units, skip this step. For example, divide 920 g per litre by 1000 millilitres per litre to find 0.92 g per millilitre. One millilitre equals one cubic centimetre, so the density of olive oil is 0.92 g per cubic centimetre. Grams per cubic centimetre is equivalent to metric tons per cubic metre, so the density of olive oil is 0.92 metric tons per cubic metre.
Multiply the density in metric tons per cubic meter by the cubic meters of material you have. For example, multiply 0.92 metric tons per cubic meter of olive oil by the amount you have: say, 500 cubic meters. Therefore, 500 cubic meters of olive oil equals 460 metric tons of olive oil.
Unless your particular material has been measured, the density and final weight in metric tons will be an estimate.
The density of water is approximately 1g per cubic centimetre. Most oils are between 0.8 and 0.9 g per cubic centimetre. However, the density of liquids tends to vary with the temperature.
For powders, granules, and other materials with air pockets, it may be prudent to use the "bulk density," which is the density of the material including the density of the air pockets. Using the normal density, your answer will be high.
If your material has a range of densities, use a number in the middle or use both numbers to create a range of weight.