The Einstein’s Equation Calculator computes the energy or mass using the famous formula E=mc2E = m c^2E=mc2, where ccc is the speed of light (3.00×1083.00 \times 10^83.00×108 m/s). By entering either the mass or energy, the calculator determines the unknown. This tool is useful for physics students, nuclear energy calculations, and understanding the mass-energy equivalence principle.