Weight Converter
Convert between 50+ weight and mass units — from atomic scales to planetary masses.
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Weight Measurement Facts & History
The kilogram was originally defined by a physical platinum-iridium cylinder kept in Paris.
Today, the kilogram is defined using the Planck constant, making it independent of physical objects.
A pound is defined as exactly 0.45359237 kilograms.
The stone, equal to 14 pounds, is still used in the UK and Ireland for measuring body weight.
One troy ounce, used for precious metals, is heavier than a regular ounce.
Einstein’s equation E = mc² shows that mass and energy are fundamentally equivalent.
Tons vs Kilonewtons: The Dangerous 'Ton' Trap in Engineering
Buying a press or calculating structural loads? 'Ton' is a dangerous word. Learn why pros use Kilonewtons (kN) and how to convert safely before you break your equipment.
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