News Desk: Many consumers are puzzled when they buy a one-litre pouch of mustard oil and find that it weighs only around 910 grams. Does this mean companies are supplying less oil? The answer lies in a basic principle of physics.
One litre does not always mean one kilogram
People generally consider one litre of water to be almost equal to one kilogram. This is because one litre of water weighs approximately one kilogram under ordinary conditions. However, the same rule does not apply to every liquid.
The reason is density. Density refers to the mass contained in a specific volume of a substance.
Mustard oil is less dense than water. Therefore, one litre of mustard oil may weigh around 910 grams. This means that a one-litre quantity of oil does not necessarily have to weigh one kilogram.
Why does mustard oil weigh around 910 grams?
The supplied information states that mustard oil has a specific gravity of approximately 0.907 to 0.910 under ordinary temperature conditions. Based on this calculation, one litre of mustard oil may weigh around 907 to 910 grams.
The density of oil can also vary depending on its temperature and composition. This is why the weight of different oils may not be exactly the same.
Government guidelines for consumers
According to the information provided, the Indian government's Department of Consumer Affairs has issued guidelines concerning the difference between the volume and weight of edible oil.
At a temperature of 30 degrees Celsius, the equivalent weight of one litre of soft oil has been specified as 910 grams.
A government directive published on June 6, 2026, has also emphasised the need to clearly mention the quantity and equivalent weight on edible oil packages. The objective is to help consumers understand the actual quantity of the product.
Are companies cheating consumers?
A one-litre mustard oil pouch weighing around 910 grams does not, by itself, indicate that a company is cheating consumers. This is because a litre is a unit of volume, while a gram is a unit of mass.
Consumers should check the Net Quantity printed on the package when purchasing oil. If the actual quantity is less than the declared quantity, they can file a complaint with the concerned Legal Metrology Department.
So, the next time a one-litre pouch of mustard oil weighs around 910 grams, there may be no reason to panic. It is a result of a basic principle of physics.
