In mouse testis, a heterogeneous population of undifferentiated spermatogonia (A) harbors spermatogenic stem cell (SSC) potential. Although GFRα1 A maintains the self-renewing pool in homeostasis, the functional basis of heterogeneity and the implications for their dynamics remain unresolved. Here, through quantitative lineage tracing of SSC subpopulations, we show that an ensemble of heterogeneous states of SSCs supports homeostatic, persistent spermatogenesis. Such heterogeneity is maintained robustly through stochastic interconversion of SSCs between a renewal-biased Plvap/GFRα1 state and a differentiation-primed Sox3/GFRα1 state. In this framework, stem cell commitment occurs not directly but gradually through entry into licensed but uncommitted states. Further, Plvap/GFRα1 cells divide slowly, in synchrony with the seminiferous epithelial cycle, while Sox3/GFRα1 cells divide much faster. Such differential cell-cycle dynamics reduces mitotic load, and thereby the potential to acquire harmful de novo mutations of the self-renewing pool, while keeping the SSC density high over the testicular open niche.