This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10⁻¹⁹ and 10⁻¹⁰ seconds.^[1]

10⁻²⁴ seconds (yoctoseconds)

Twenty-three yoctoseconds is the time needed to traverse a 7-femtometre distance at the speed of light—around the diameter of a large atomic nucleus.

10⁻²¹ seconds (zeptoseconds)

10⁻¹⁸ seconds (attoseconds)

10⁻¹² seconds (picoseconds)

10⁻⁹ seconds (nanoseconds)

10⁻⁶ seconds (microseconds)

10⁻³ seconds (milliseconds)

10⁰ seconds

10³ seconds (kiloseconds)

10⁶ seconds (megaseconds)

10⁹ seconds (gigaseconds)

10¹² seconds (teraseconds)

10¹⁵ seconds (petaseconds)

10¹⁸ seconds (exaseconds)

10²¹ seconds (zettaseconds)

10²⁴ seconds (yottaseconds)

10²⁷ seconds (ronnaseconds)

10³⁰ seconds (quettaseconds)

The half-life of tellurium-128 is over 160 trillion times greater than the age of the universe (which is 4.35×10¹⁷ seconds).^[6]