The kilogram may need to go on a diet. The international standard, a cylinder-shaped hunk of metal that defines the fundamental unit of mass, has gained tens of micrograms of MASS from surface ...

When we measure the world, we measure it using base units like 'foot,' 'mile,' 'meter,' and 'second.' But who decides how big those units of measurement are? In the United States, those units are ...

The new kilogram has finally arrived. Updates to scientists’ system of measurement went into force May 20, redefining the kilogram and several other units in the metric system. The revamp does away ...

It’s one of those things where if you think about it too much, your head might explode. We know there are 1,000 grams in a kilogram, and 1,000 kilograms in a metric ton, but how was it ever decided ...

The kilogram has the dubious distinction of being the only SI unit still based on a physical object; specifically, a metal cylinder kept in a vault in France. Plans are well underway to redefine the ...

The official US kilogram — the physical prototype against which all weights in the United States are calibrated — cannot be touched by human hands except in rare circumstances. Sealed beneath a bell ...

The supreme arbiter of mass for humankind is a polished cylinder of platinum alloy just smaller than a golf ball. It was cast in London in 1879, unveiled a decade later in a ceremony in France, and ...