# How we measure a kilogram is about to change

A small metal cylinder known as the “international prototype of the kilogram” has been the standard for measuring weight for over 100 years.

The platinum-iridium cylinder, pictured above, weighs 1kg and is looked after by the International Bureau of Weights and Measures.

“It is the defining mass against which all other kilograms are measured,” stated The Guardian, reporting on the fact that this is measure is soon to be changed.

The international General Conference on Weights and Measures will be held later this month in France and its delegates are reported to adopt “a fundamental measurement defined in terms of an electric current in order to define the mass of an object”.

The “Kibble balance” technique measures the electric current required to produce an electromagnetic force equal to the gravitational force acting on a mass, stated the report.

A “fundamental constant” known as the Planck constant will then be used as the measure for the weight.