The Radioactive Decay Calculator is a simple and reliable tool that helps you calculate the remaining quantity of a radioactive substance, its decay constant, or the elapsed time using the radioactive decay formula N = N₀ × e^−λt. This calculator is useful for understanding how unstable isotopes lose energy over time through nuclear decay. It’s ideal for students, teachers, and scientists studying nuclear chemistry, radiometric dating, or radiation physics. By knowing the decay constant (λ) and the initial amount (N₀), you can easily determine how much of a sample remains after a given period. Use this calculator to explore half-life concepts, exponential decay behavior, and the stability of radioactive materials in a clear and interactive way.