Mass-Energy Equivalence Calculator (E = mc²)
Connects mass and energy through Einstein’s equation.
Answer
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Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Energy —
Mass —
In kilowatt hours — kWh
In tons of TNT — t TNT
The formula
E = m c²
c is exactly 299,792,458 m/s. A ton of TNT is defined here as 4.184 × 10⁹ J. This is the total rest energy; ordinary reactions release only a tiny part of it.
What to watch out for
Nuclear fission turns only about 0.1% of the fuel’s mass into energy. Only matter and antimatter convert it all.
Frequently Asked Questions
How much energy is in 1 g of mass?
89,875,517,873,682 J, or 24,965,422 kWh, equal to about 21,481 tons of TNT.
How much mass does a kilowatt hour weigh?
4.006×10^-11 kg, far too small to measure.