We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (ρ parameter) for present and future pp andpp colliders, and on total cross sections for γp → hadrons at cosmic-ray energies and for γγ → hadrons up to √ s = 1TeV. These predictions are based on an extensive study of possible analytic parametrisations invoking the biggest hadronic dataset available at t = 0. The uncertainties on total cross sections, including the systematic errors due to contradictory data points from FNAL, can reach 1.9%at RHIC, 3.1% at the Tevatron, and 4.8% at the LHC, whereas those on the ρ parameter are respectively 5.4%, 5.2%, and 5.4%.