We develop a mass formula for finite lumps of strange quark matter near flavor equilibrium. Our Fermi-gas model includes surface tension and Coulomb energy but not quantum-chromodynamic radiative corrections. Assuming strange matter is stable in bulk, we investigate the radioactive decays of finite strangelets (clumps of strange matter with baryon number Aapprox. <10/sup 7/). We derive conditions governing instability for all decay modes. The regions of baryon number, charge, and hypercharge in which various decays are allowed are illustrated graphically, and flow lines and accumulation lines for decaying strangelets are obtained. Finally, we present typical histories of decaying strangelets.