For more than a century, a single metal cylinder in a Paris vault quietly defined what a kilogram was. After 130 years, ...

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 ...

In a subterranean vault in a suburb of Paris lies a small, rarely seen metal cylinder known as Le Grand K. For 130 years, this golf-ball-sized hunk of 90% platinum and 10% iridium has served as the ...

The 'one kilogram to rule them all' was cast in platinum and iridium in 1879 and is kept in a triple-locked vault THE world says goodbye to the original kilogram on May 20, on World Metrology Day.

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 ...

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 ...

GAITHERSBURG, MD. — Forty feet underground, secured in a temperature- and humidity-controlled vault here, lies Kilogram No. 20. It’s an espresso-shot-sized, platinum-iridium cylinder that is the ...

After more than a century, the international prototype kilogram – a cylindrical chunk of metal stored in a French vault – doesn't weigh the same as its 40 replicas, distributed worldwide and used to ...

How much is a kilogram? 1,000 grams. 2.20462 pounds. Or 0.0685 slugs based on the old Imperial gravitational system. But where does this amount actually come from and how can everyone be sure they are ...