Calculate the energy equivalent of any mass using Einstein's most famous equation. Understand the enormous energy locked inside even tiny amounts of matter.
Einstein's equation E=mc² tells us that mass and energy are two forms of the same thing — and that mass can be converted into energy, and energy into mass. The c² term (speed of light squared) is an astronomically large number, which means even a tiny amount of mass contains an enormous amount of energy.
One kilogram of any material — rock, water, iron — contains 89.88 petajoules of rest energy. That is equivalent to about 21.5 megatons of TNT — the same as the largest nuclear weapon ever detonated (Tsar Bomba was 50 megatons from ~2.4 kg mass converted).
In nuclear fission, uranium nuclei split and the products weigh slightly less than the original. This "mass defect" is converted to energy via E=mc². In the Sun, hydrogen nuclei fuse into helium — losing 0.7% of their mass as pure energy, powering our entire solar system.