How much energy is in matter?

Einstein's mass–energy equivalence, E = mc², with c = 299,792,458 m/s so that every kilogram of mass is worth 89,875,517,873,681,764 joules if converted completely. This is not a promise that an ordinary object can release all of this energy — complete conversion is a useful theoretical comparison, not something real processes achieve; nuclear fission converts only a tiny fraction of a percent of its fuel's mass, for instance.

Sources: TNT's yield (4.184 MJ/kg) is the defining value behind the “tons of TNT” unit; gasoline's (≈46 MJ/kg) is a standard lower-heating-value figure for motor fuel. Uranium–235 fission is calculated from 200 MeV released per fission event, a standard nuclear-physics figure. Hydrogen fusion uses the widely-cited ≈0.7% mass-to-energy conversion of the Sun's proton–proton chain. Matter–antimatter annihilation is definitionally 100%. China's total annual energy supply (used to calibrate the “½×” mass preset and its own row in the table) — 168,386,888 TJ in 2023, the largest of any country or region — is from the IEA's World Energy Balances. An average Canadian home's annual energy use, 87.6 GJ (2023), is from Natural Resources Canada. The Ford F-150 round trip assumes a ≈4,600 km one-way driving distance between Vancouver and Montreal and ≈12.5 L/100 km combined fuel consumption. The hamster-wheel figure assumes roughly 1 W of mechanical output over 30 minutes, a rough order-of-magnitude estimate, not a measured figure. The marathon figure uses a commonly-cited ≈2,600 kcal gross energy expenditure for an average runner completing 42.195 km.