In this talk we discuss \textit{solar} neutrino mixing sum rules, arising from charged lepton corrections to Tri-bimaximal (TB), Bi-maximal (BM), Golden Ratios (GRs) and Hexagonal (HEX) neutrino mixing.
We also discuss \textit{atmospheric} neutrino mixing sum rules, arising from preserving one of the columns of the above types of mixing.
We consider the sum rule predictions for $\theta_{12}$ and the cosine of the Dirac CP phase $\delta$,
in terms of the other mixing angles, using up-to-date global fits of the neutrino oscillation data.
We also consider Littlest Seesaw models, based on constrained sequential dominance CSD($n$) with $n=2.5$, $n=3$ and $n \approx 3.45$ (the latter favoured by modular symmetry),
using a new analysis to accurately predict the observables $\theta_{12}$, $\theta_{23}$ and $\delta$.