The current and field profiles and the perpendicular susceptibility of a thin type-II superconducting strip of thickness t and width 2a in the Meissner state are calculated numerically by minimizing the sum of magnetic and kinetic energies. In terms of the two-dimensional screening length Λ = 2λ2/t, where λ is the London penetration depth, proposed by Pearl, effective penetration depths with respect to the field and current, λeff,H and λeff,I, are introduced. It is found that λeff,H/a ≈ 1.18(Λ/a)0.49 and λeff,I/a ≈ 5.2Λ/a hold at low values of Λ/a. Various features and applications of the calculated results are discussed. © IOP Publishing Ltd.