This paper describes quantitatively the influence of the self-field and the cross-sectional geometry on the effective critical current and the ac losses in transport current applications of nontwisted multifilamentary Bi-2223/Ag conductors. The results are obtained with finite-element method simulations. The numerical implementation includes an anisotropic model for the dependence of the critical current density Jc and the power index n on the local parallel and perpendicular magnetic field components. The relation is given between the intrinsic critical current density and the effective critical current for different multifilamentary conductors. Shown are examples of the current and magnetic flux density distributions in order to demonstrate their effect on the ac losses in self-field.