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Weight and Volume Converter

Convert between units of weight and volume using this calculator tool. If you wish to convert cooking ingredients, give our cups to grams or main cooking converter a try.

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How to convert weight to volume

To convert weight (mass) to volume, divide the mass of the substance by the density. Volume = Mass ÷ Density. For this to work, the density must be defined using the same units of mass and volume as referenced in the rest of the formula. As an example, Volume (m3) = Mass (kg) ÷ Density (kg/m3)

How to convert volume to weight

To convert volume to weight (mass), multiply the volume by the density of the substance. Mass = Density × Volume. For conversions to work, the units of mass and volume referenced in the formula must match with the density. For example, Mass (lb) = Density (lb/ft3) × Volume (ft3).

How much does a gallon of gasoline weigh?

Using a gasoline density of 750kg/m³, a US gallon of gasoline weighs around 2.84kg (6 ¼ pounds).

Explanation: First, we convert m³ to US gallons (264 US gallons to the cubic meter/metre), which gives us a density of 750/264 = 2.84kg/gallon. Now, we can put our equation together: Mass = Density × Volume. So, 2.84 × 1 (gallon) = 2.84kg.

If you want to convert gallons of gasoline to pounds, give our gallons to pounds converter a try.

Converting between volume and weight (actually mass)

Converting between units of weight and volume isn't as simple as it sounds. This is because they are different types of units. As an example, the ton is a unit of mass and the liter/litre is a unit of volume. Equally, the cup is a unit of volume and the gram a unit of mass. Note the reference of 'mass' and not 'weight' here - they are commonly used interchangably, but their meaning is actually quite different. You can read more about that in our article about mass and weight.

To complete a conversion between units of volume and mass, you have to factor in the density of the substance that you are trying to convert and include that in your calculation. The reason for this is obvious - a cup of feathers will weigh less than a cup of crude oil. So, the substance density is important for an accurate conversion. As is the temperature of the substance, where liquids are concerned.

For those people looking for the density formula for converting volume to weight, and vice-versa, it looks like this (adapted from answers.com):

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)

Weight to volume conversion substances

All of the 'Substance Density List' figures for this weight and volume converter have been researched from simetric.co.uk. With grateful thanks to Roger Walker.

If you would like to convert a volume of water (gallon, liter, cup or tablespoon) to pounds, ounces, grams or kilograms then please give our water weight calculator a try. And if you would like to find out about the weight of water, we have an article discussing how much a gallon of water weighs.

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If you have any suggestions or queries with this weight and volume conversion tool, please contact me.