How much radiation does a banana emit?

The story behind the answer

0.1 microsievert is correct because bananas naturally contain potassium-40, a mildly radioactive isotope. The tiny dose you receive from a banana—about 0.1 μSv—is known as the “banana equivalent dose,” a handy way to illustrate how small everyday radiation exposures are.

For context, typical daily background radiation is around 6–10 μSv, a chest X‑ray is about 100 μSv, and a transatlantic flight can be tens of μSv. Your body tightly regulates potassium, so any extra from a banana is quickly balanced out, making the dose both real and harmless.