Abstract—Analytical expressions for the scalar magnetic potential vs. variation of magnetization in the pole of a thin-film magnetic head, pole dimensions, and the horizontal and vertical pole positions relative to the plane of the hard-disk working layer were established. Expressions for the magnetic stray fields vs. the horizontal and vertical poles were obtained by studying the pole domain structure vs. the external magnetic field and determining the domain of magnetization variation in the pole marginal zones vs. the external field. Expressions for the write fields of the thin-film heads were established as a superposition of the pole stray fields. Examples of calculations of the write fields were given for various kinds of the thin-film magnetic heads.