A measurement is presented of the inelastic proton–proton cross section at a centre-of-mass energy
of √s = 7 TeV. Using the CMS detector at the LHC, the inelastic cross section is measured through two
independent methods based on information from (i) forward calorimetry (for pseudorapidity 3 < |η| < 5),
in collisions where at least one proton loses more than 5 × 10−6 of its longitudinal momentum, and
(ii) the central tracker (|η| < 2.4), in collisions containing an interaction vertex with more than one, two,
or three tracks with transverse momenta pT > 200 MeV/c. The measurements cover a large fraction of
the inelastic cross section for particle production over about nine units of pseudorapidity and down to
small transverse momenta. The results are compared with those of other experiments, and with models
used to describe high-energy hadronic interactions.