  A linear universal decay formula is presented starting from the microscopic
mechanism of the charged-particle emission. It relates the half-lives of
monopole radioactive decays with the $Q$-values of the outgoing particles as
well as the masses and charges of the nuclei involved in the decay. This
relation is found to be a generalization of the Geiger-Nuttall law in $\alpha$
radioactivity and explains well all known cluster decays. Predictions on the
most likely emissions of various clusters are presented.
