Utilitarianism plays a central role in economics, but there is a gap between theory, where it is dominant, and applications, where monetary criteria are often used. For applications, a key diculty for utilitarianism remains to define how utilities should be measured and compared across individuals. Drawing on Harsanyi's approach (Harsanyi, 1955) involving choices in risky
situations, we introduce a new normalization of utilities that is the only one ensuring that: 1) a transfer from a rich to a poor is welfare enhancing, and 2) populations with more risk averse people have lower welfare. We embed these requirements in a new characterization of utilitarianism and study some implications of this "fair utilitarianism" for risk sharing and collective risk aversion.