A procedure is being developed for analyzing bubble circuits, based on periodic arrays of I‐bars as building blocks for more complex elements. This paper describes a method for solving the basic I‐bar magnetostatic problem, based on the simultaneous solution of Poisson’s equation and an equation of magnetic equilibrium. The solution uses a Fourier series approach which lends itself to spatially nonuniform applid fields, as caused by bubbles. The mathematical formulation of the bar geometry is in 3‐dimensions, with magnetization modelled along one axis, the major axis dominating. A numerical simplification results from analytically averaging the demagnetizing fields across the transverse axis, an 80‐harmonic calculation of an I‐bar array requires 5 seconds of computer time. Results compare well with others for I‐bars in uniform fields and for the potential well of a bubble on an I‐bar. In a new result with implications for analysis of logic gates, energy minima are found for two bubbles on opposite ends of an I‐bar.