Flavor hypercharge ($Y=B+S$)

The additive flavor symmetry quantum number $Y=B+S$ combines baryon number with strangeness. For the $(u,d,s)$ quark triplet its values are $(1/3,1/3,-2/3)$. The Gell-Mann--Nishijima formula is $Q=I_3+Y/2$. This is distinct from the normalization of electroweak hypercharge.

For the light quark flavors, electric charge is $Q=I_3+Y/2$, with flavor hypercharge $Y=B+S$. On $(u,d,s)$ it gives $(2/3,-1/3,-1/3)$, and additivity extends it to the baryon octet and meson octet.