The cylindrically symmetric bubble domain bounded by a one-dimensional 180°Bloch wall is analyzed based on a micromagnetic theory. The magnetization distribution in a wall and the bubble energy are calculated as functions of the plate thickness and material parameters. The energy of a bubble (energy relative to that of a saturated platelet) is found to be small (10 -5 erg for orthoferrites) compared to the individual energy (magnetostatic, exchange, and anisotropy) terms. The wall thickness is approximated reasonably well by (A/K)1/2. Bubbles with thicker walls yield lower energy and larger wall mobility but bubble size is not affected. It is concluded that Thiele's results of assuming zero wall thickness are valid since the bubble size is nearly independent of wall thickness. © 1971 The American Institute of Physics.