  In this paper we discuss the main principles of magnetic design for
superconducting magnets (dipoles and quadrupoles) for particle accelerators. We
give approximated equations that govern the relation between the
field/gradient, the current density, the type of superconductor (Nb-Ti or
Nb3Sn), the thickness of the coil, and the fraction of stabilizer. We also
state the main principle controlling the field quality optimization, and
discuss the role of iron. A few examples are given to show the application of
the equations and their validity limits.
