Interactive Half-Life Calculator

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A thing’s half-life is how long until only half of it is left. It’s used in radioactive decay, medicine, and many other things. Remember:

  • Hazards in radiation are proportional the rate at which energy comes out.
  • Short half-lives imply energy is coming out quickly, and are the primary hazard.
  • Long half-lives imply energy is coming out very slowly, and are less of a hazard. For example, you can hold long half-life isotopes of natural uranium in your hand without accumulating a hazardous dose.
  • In the extreme, an infinite half-life would mean energy never comes out, representing zero radiological risk.

Learn more about the math here.

This graph depicts a single nuclide with its single half-life decaying to stability. Nuclear waste is typically composed of thousands of different nuclides that each have their own unique half-life, and often decay to other radioactive daughter nuclides before making it to stability.

Learn about solutions to nuclear waste here.