How To Convert Volume To Weight

Article Category: Units

Last updated: 19 December 2011

A frequent question posted to our forum is "how can I convert a volume to a weight?" Most commonly, people are trying to find out how to convert from metric tons to liters - often for substances such as water, gas and oil. Emails also arrive from people who are trying to measure out cooking ingredients and need to convert from grams to teaspoons or cups.

Confusion With Converting Weight To Volume - photo
The problem with this type of conversion is that it isn't as simple as it sounds. For example, a metric ton is a unit of weight and liter is a unit of volume. To complete a calculation such as this, you need to be able to factor in the density of the substance that you are looking to convert and include that in the formula calculation.

For those people looking for the formula for converting volume to weight, and vice-versa, it looks like this (adapted from

"Density = mass/volume (ρ=m/V). So V=m/ρ and has units (kilograms)/(kilograms per cubic meter)=cubic meter.

If you are dealing with other units, say pounds, as a unit of weight, 'then 1 kg corresponds to 2.21 lb at sea level in the sense that the weight of 1 kg is 2.21 lb at sea level. Similarly 1 lb corresponds to 453.6 g and 1 oz to 28.35 g' (Beiser, A. Physics, 5th ed, Addison Wesley, 1992)"

Before you can go any further with your calculation, you need to find out the density of the substance that you are trying to convert. You should be aware that densities vary based upon temperature, where liquids are concerned.

To help you out with your conversion, we have developed a weight to volume converter. On the converter page, we have included a list of substances and density approximations for some common liquids, materials, metals and woods.

Alastair Hazell
The Calculator Site

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