For two independent principles of intergenerational equity, the implied discount rate equals the growth rate of real per-capita income, say 2%, thus falling right into the range suggested by the U.S. Offce of Management and Budget. To prove this, we develop a simple tool to evaluate small policy changes affecting several generations, by reducing the dynamic problem to a static one. A necessary condition is time-invariance, which is satisﬁed by any common solution concept in an overlapping generations model with exogenous growth. This tool is applied to derive the discount rate for cost-beneﬁt analysis under two different utilitarian welfare functions: classical and relative. It is only with relative utilitarianism that the discount rate is well-deﬁned for a heterogeneous society, is corroborated by an independent principle equating values of hugrowth rate of real per-capita income.